How many of those you've got there?

what kind of specs are we talking here, should we be recommending new games or classics or both? 

pick up Magika it's great if a little buggy, especially if you are a movie buff the amount of trivia in the game is insane lol, it's also laugh out loud funny and has innovative gameplay.

Starcraft 2 is also very good highly reccomended, you may also want to give Warcraft 3 a try you can probably pick it up cheap and it's RTS/RPG campaign is actually very good.

You could give the Witcher a spin it's a bit of a grind and gameplay isn't the best but the shades of grey moral choices and the world it's set in is very compelling. Most of the quests are fetch quests tho and the game takes a while to get going. Also the sequil is coming out soon and looks AMAZING...

Mount & blade is also worth a spin, you should get the warband version rather than the origonal also there is a new stand alone expansion coming this year so you could probably wait for that...

Little Big Adventure 1 & 2  (Only the sequel is exclusive)

Rome: Total War

Heroes of Might and Magic III

So have you found anything you like?

do you want more reccomendations? 

Sim City
Sim City 2000
Sim City 3000 Ultimate
Sim Tower
Yoot Tower
Sim Copter
Sim Farm
Indiana Jones and the Fate of Atlantis
Maniac Mansion: Day of the Tentacle
Sam and Max Hit the Road
Full Throttle
Mega Race
Software Toolworks Star Wars Chess
Software Toolworks Mario is Missing
Star Wars Rebellion
Star Wars Yoda Stories
Jedi Outcast
Jedi Academy
Tie Fighter
Age of Empires II
Age of Empires III
Company of Heroes
Warcraft
Warcraft II
Diablo II
League of Legends
Roller Coaster Tycoon
Roller Coaster Tycoon II
Combat Flight Simulator 2
Counter Strike
Portal
Battlefield 1942/Desert Storm
Battlefield II

There's a start.

Get Shogun Total War 2! Trust me its a real time sink and a hugely addictive game. Similiar to Civ 5 but with an added real time combat element.

Civilization series - especially Civ IV is pretty awesome. Try the demo, I can almost guarantee you'll like it no matter what you think of the series right now.

Total War series - Rome is still one of the better games in the series but you might also want to check out the newest game, Shogun 2. I often hear people call it the best game in the series since Rome.

S.T.A.L.K.E.R. might do it. I'd say it mixes survival, FPS and RPG pretty nicely.

The first Crysis and its open levels are pretty fun. You won't find a great story there but at least you'll get a great game.

Enemy Territory: Quake Wars is not exclusive but the console versions are far inferior and you should definitely try Quake Wars. It's team-based action, a bit like Team Fortress 2 if you had no idea before. You can also check out its free predecessor, Wolfenstein: Enemy Territory.

Titan Quest is a nice Diablo clone. Or you can just stick to Diablo II if you wish, it's still very popular.

Also, some epic RPGs: Baldur's Gate series (especially BG2), Planescape: Torment, Fallout series (the older games), Arcanum, or if you prefer more combat and less story, why not the Icewind Dale series.

I'd also like to recommend Emperor: Rise of the Middle Kingdom. It's an older city-building game, set in China set in... Well, it begins when China began and ends in... I'm not sure, in the 17th century?

starcraft II is all you will ever need.

/thread

Rome Total War, the most awesomesauce RTS I've played so far, also Civilizations are pretty good too, I found Rise of Nations reasonably decent if a bit outdated now.

Counter Strike 1.6/Source are good competitive FPS games, with large modding community and just community in general, Battlefield 2 is an awesome game too.

-Action/adventure

Batman Arkham Asylum

Ninja Blade

Alien Breed (I hope you have an xbox 360 joystick)

Darksiders

Dead Space

Gears of War

-Adventure Point and Click

Machinarium

The Monkey Island 1 and 2 (Special Edition)

Full Throtle

Grim Fandango (incredible game and  you wont need a powerful PC for this)

Flight of the Amazon Queen

Indiana Jones and the fate of Atlantisds

Indiana Jones and the last crusade

Beneath a Steel Sky

Broken Sword 1 and 2 (AMAZING games!)

-RPG

The Last Remnant

The Witcher

Mass Effect 1 and 2

Fallout 2 and 3

Oblivion

-Platformer

Braid

Bionic Commander Rearmed