The races of Tamriel are far stronger than the D&D 3.5 races. I haven't given them any LA, since I'm not comparing them to PHB races.
ARGONIAN
Argonians (or Saxhleel in Jel, their native tongue, a word that seems to mean "People of the Root") are the reptilian denizens of Black Marsh. Little is known and less is understood about them. Years of defending their borders have made the Argonians experts in guerrilla warfare, and their natural abilities make them equally at home in water and on land. They have developed natural immunities to the diseases and poisons that have doomed many would-be explorers and conquerors of the region. Their seemingly expressionless faces belie a calm intelligence, and many Argonians are well-versed in the magical arts. Others rely on stealth or steel to survive, and their natural agility makes them adept at either. They are, in general, a reserved people, slow to trust and hard to know, yet they are fiercely loyal, and will fight to the death for those they have named as friends.
Racial Traits
All Argonians share the following racial traits:
ò +2 Dex, +2 Int, -2 Cha, -2 Con. Argonians are swift and calmly intelligent, but their alien looks and physiology are offsetting.
ò Blood of the Hist (Ex): Argonian blood is naturally resistant to disease, granting them a +2 bonus to all saving throws against disease. Note that the penalty to Constitution does not affect their Fortitude saves against disease.
ò Poison Immunity (Ex): Argonians are immune to all magical and non-magical poisons.
ò Gills (Ex): Argonians have a hidden set of gills, enabling them to breathe water freely.
ò Histskin (Su): Once per day, Argonians can gain the power of the Hist, granting them fast healing equal to their Constitution modifer for one round per character level.
ò Favored Class: Duskblade.
Argonian Characters
Swift and intelligent, Argonians make excellent thieves and mages.
Adventuring Argonians: Argonian adventurers are a rare breed. Most Argonians are relatively backward tribal people, more concerned with agrarian welfare than the world around them. Adventuring Argonians tend to be young and curious, and eager to explore other lands apart from their damp realm. Some may have darker interests in mind than others, though.
Argonian adventurers generally face mild hostility from Dark Elven communities, especially rural ones. More cosmopolitan lands, such as Cyrodiil, treat Argonians as curious objects of interest, although small communities of Argonians are not uncommon.
Character Development: Given their racial bonuses, Argonians are well-suited for the duskblade class, blending steel and spell. Many Argonians also become wizards and rogues, taking feats that enhance their respective abilities. Spellswords and arcane tricksters are natural prestige class choices.
Argonian religion is unknown for the most part, but Argonian druids exist. Argonians born under the Shadow constellation, however, are spirited away to join the Dark Brotherhood and serve Sithis as assassins.
Character Names: Argonian names tend to be rather descriptive. Examples include Skin-in-Tree's-Shade, Grey-Throat and Sings-like-Thunder. Some follow a more exotic naming pattern, such as Ajun-Kajin, Dar-Ma and Teekeeus.
BRETON
Bretons are the human descendants of the Aldmeri-Nedic Manmer of the Merethic Era and are now the inhabitants of the province of High Rock. They are united in culture and language even though they are divided politically, for High Rock is a factious region. Bretons make up the peasantry, soldiery, and magical elite of the feudal kingdoms that compete for power. Many are capable mages with innate resistance to magicka. They are known for a proficiency in abstract thinking and unique customs. Bretons appear, by and large, much like other pale-skinned humans. They are usually slight of build and not as muscular as Nords or Redguards. Their Elvish ancestry is usually only detectable upon a closer inspection of their eyebrows, ears, or high cheekbones, though many individual Bretons appear to be more Nordic or Imperial than anything else. The great diversity in their appearance is to be expected from their politically fractured society, though their clothes, accents, customs and names are fairly uniform.
Racial Traits
All Bretons share the following racial traits:
ò +2 Int, +2 Cha, -2 Str, -2 Con. Bretons tend to be intelligent and flamboyant, but not as physically capable as other races.
ò Arcane Aptitude(Ex): Bretons are famous for their quick and perceptive grasp of Spellcraft. They have a +2 bonus to Spellcraft checks and always treat Spellcraft as a class skill.
ò Magical Talent (Ex): Bretons are skilled in the magical arts. They have an innate +1 bonus to the DCs of their spells.
ò Spell Resistance: Even the least Bretons prides himself in his innate resistance to magic. All magical damage taken by Bretons is reduced by -1 per damage die. Spells that inflict ability damage, drain and negative levels are treated as though the damage die is one step lower.
ò Dragonskin (Su): Once per day, a Breton may grant himself a +1 bonus to AC per four character levels. This bonus lasts for 1 round per two character levels.
ò Favored Class: Wizard.
Breton Characters
Passionate and eccentric, poetic and flamboyant, intelligent and willful, the Bretons feel an inborn, instinctive bond with the mercurial forces of magic and the supernatural. Many great sorcerers have come out of their home province of High Rock. Bretons are said to enjoy intellectual pursuits; they often have an affinity for anything related to logic and ordered complexity. Their love of knowledge and affinity for commerce drives them into a host of careers, including trading, the military, sailing, medicine, textiles, manufacturing, writing, theology, philosophy, banking, all kinds of artistry, and other scholarly pursuits.
Adventuring Bretons: Bretons quest for many reasons, as questing is part of the cherished traditions in the jockeying of power among High Rock's feudal hierarchy. Bretons have adventured all over Tamriel, and many use their magical talents to fuel their success. They are a well-regarded people, although there exists deep enmity among Bretons and Redguards.
Character Development: Bretons make excellent wizards and sorcerers, due to their innate grasp of spellcraft and beneficial ability score bonuses. Breton spellcasters often take feats that enhance their magical prowess or apply their arcane craft in a more economic manner, such as crafting magic items and offering enchanting services. Breton wizards tend to specialize in Conjuration, Divination, Necromancy and Transmutation, with Enchanters and Illusionists being a close second. Necromancy may seem an odd choice to specialize, due to the grislier aspects of the school, but many Breton mages are fascinated by the mystic nature of the soul and magic surrounding it view necromancy as a perfectly valid path.
That High Rock is the home of the legendary archlich and necromancer Mannimarco may also play a part in matters regarding the Necromancy school.
Evocation specialists are rare. While Bretons accept Evocation as a perfectly valid and respectable school of magic, they tend to view the other schools of magic as being more intellectually stimulating and challenging, due to the more varied applications inherent in them.
Breton clerics are rare, but the few that do follow the path of the divine worship gods of magic.
Character Names: Breton names tend to sound European. Examples include Francois Mottiere and Frizkav Brutya.