Remember it was designed to run on the 360, so specs are fairly light. Depending what res you wanted to play at you should be fine with most any fairly current GPUs. My system flys with it.
I don't have things maxed, they did offer 'beyond 360' options for PC, but I have no trouble at all running with base options + high textures, high water, all water effects on, blood high (Fatality!), and all the fade type things at ~60% of max (default is like ~25%).
The guide is helpful, but they don't list the game classes. Tons of other info not in the basic manual to help you out. I'd guess 2/3 of the book are dungeon maps.
*hides eyes from peeping those pages* Pretty worth the $ for someone who wants to know how to enjoy all the game has to offer. (Today I am considering starting a Thief type person to enjoy the ... city game aspects
)
All that being said... for those who can't find a good base class...
"Paladin" - heavy combat + healing
Specialization: Combat
Class attributes: Strength, Endurance (To a smaller extent Agility)
Skills: Armorer, Blade, Block, Heavy Armor, Marksman, Sneak, Restoration
"Shade" - stealth specalist and city... explorer
with magic backup
Specialization: Stealth
Class attributes: Agility, Willpower
Skills: Armorer, Marksman, Security, Sneak, Light Armor, Alteration, Restoration