I would play:
Battlezone 1 & 2
Dungeon keeper 1
Discworld (point and click one)

i hope they get more adventure games soon, or any at all:
broken sword series is the one i'd like the most.

My wish list contains the following games:
(a) Blade Runner
(b) Sanitarium
(c) Goblins (1 st, 2 nd and 3 rd part)
(d) Disc World (1 st, 2 nd and noir)
(e) Dreamweb
(f) Mechwarrior

Games I have heard about but never got to play that I would buy;
System Shock
Grim Fandango

System Shock Series
Baldurs Gate Series
Icewind Dale Series
Planescape Torment
Syndicate Wars
Shadow Warrior

Most of these were already mentioned, but I figure that is okay. Shows desire
Blood Omen: Legacy of Kain
The X-Wing and TIE Fighter games
Star Crusader (with expansion). And preferably manual :p. I would pay 10 bucks for the manual alone (damn scanning and stealth), let alone a way to play it without powering up my 486.

I have a lot of the games mentioned, but would get them here again cheap if I couldn't get them to play nice with vista, or I was just annoyed using a cd... ha.
Anyway, the two games I missed (shame on me) that I would buy in a heartbeat would be the Icewind Dale games and Grim Fandango.

Police Quest series
(pretty much all the Quest games, really)
Planescape Torment
Wing Commander I-IV
System Shock I and II
X-Wing
TIE Fighter
Autoduel
Ultima Underworld
X:Com series
Tetris (the original)
Simcity 2000
Elite
Frontier: Elite II
Populous II
Syndicate Wars
Dark Forces
Jedi Knight
Duke Nukem 3D
Age of Empires

Here is my list as far as i can remember now:
Syndicate wars,
System Shock 1 & 2
Dungeon Keeper 1 & 2
Battlezone 1 & 2
Broken Sword Series
Metal Gear Solid
Final Fantasy VII & VIII
Shadow Warrior

planetscape torment is a must!

Some have already been mentioned:
Colonization. Yes please.
Savage Empire. Good ole roleplaying/adventure game. Highly detailed game, I spend ages in.
Wing Commander Series. Oh how I'd love to see that again. I'd even pay full retail price for a Windows version again. Properly amongst my top 3 most played ever.
Indiana Jones 3+4 adventure games.
Edit:
Forgot about
Railroad Tycoon 1+2, the by far best of the RR Tycoon games in my opinion.

Check 3DRealms.com for that one ;-)
Some great additions would be:
Quest for Glory series, since Sierra doesn't want to release them themselves
Dune
Dune II: Battle for Arrakis
Dune 2000
Dark Seed (1 and 2)
Estatica
Legend of Kyrandia games
And I could go on and on and on... :-)

wing commander 3 i would love to see that game on here,no cd swapping now that is a dream come true :)

Just a few I'd love to see...
Lemmings (and the sequels)
The Lost Vikings (and the sequel, Norse by NorseWest)
ARCHON - The Light and The Dark
It's a pity that the very best 2D version of Worms (The Director's Cut) was only ever released for the Amiga. Gotta love the Sheep Strike... ["Death by mutton from the skies!"]

I'm gonna have to add another vote for the Classic Lucasarts titles like Sam and Max, Full Throttle, Grim Fandango, the monkey Islands, etc.
Also, if Final Fantasy 7 and 8 were available that would be amazing.
Oh and how could I forget the Thief games!?
Ooh... and Halo PC.