Must play pc games?

sup' guys

just recently i've been getting into pc games after a lifetime of playing on consoles and i was wondering what are some of the "must play" pc games, currently playing through Deus Ex and its pretty damn awesome.

if its relevant my system specs are:

AMD phenom x3 2.1ghz
ati 4850 512mb
4gb ram

anyway any suggestions would be awesome.

thanks in advance dudes

You could try giving Just Cause 2 and Metro 2033 a whirl, and yeah, Deus Ex is awesome, waiting for the third one. The second one is all right but not as in-depth as the first. The only thing I liked about the second one however is that you were actually allowed to choose which organisation you worked for and you weren't inevitably forced down a path like in Deus Ex.

Hmmm lets see
Doom
quake
Unreal
Half life 1,2 ,epi1, epi2
TF2
L4D 1/2
BF BC 2 has a huge community right now.
Portal
Crysis
Counter Strike
Deus Ex
World of Goo
Guild wars
Sins of a Solar empire
Mass Effect 1 and 2
Fallout 3
Warcraft III
Diablo 2
Starcraft
WoW (might as well)
Dragon Age
Kotor

Thats all I can think of now...
I'll think of more later

Thanks for all of the suggestions guys, will be sure to check them all out.

Ohhh I misread, I thought you meant what are the 'current must-play' games, not of all time :P

Elder Scrolls' 3&4 (I haven't played any earlier myself)
Battlefields are good
SupCom2
You could try Eve but that's pretty in-depth (Requires a lot of time).

Pathogen pretty much listed all the decent ones anyway....

dont really mind what era they are from as long as they will play reasonably well on my system.

SHIT! How could I have forgotten Elder Scroll

I was thinking the same thing tbh, I was like "He seems to like some awesome games, but he forgot ES?"

Wow, insta-reply ftw. I was just checking my mail and it was in there :P

So no one mentioned

Duke Nukem 3D
Return to Castle Wolfenstien
Neverwinter Nights
Baldurs Gate
Temple of Elemental Evil
Age of Empires
Hexen
Fallout 1 & 2
Drakensang
Borderlands
S.T.A.L.K.E.R (dont bother with the expansions)
Warhammer 40K
AVP (the old ones)
Star wars Dark Forces
KOTOR 1 &2
Call of Duty
Turok
Blood
Pool of Radiance
Farcry

and all of you who havnt tried ES 1&2 should. Their free anyways.

Where's GTA San Andreas? BTW, that setup is nice

Fable : The Lost Chapters is pretty entertaining, and the sims series if you like making virtual babies starve cough i mean making a  family that contributes to society.