I was feeling nostalgic recently so I made a list of all the games I have either owned or that a friend let me borrow/keep (this only includes games with the original disks and, if appropriate, manual), and thought it might be of interest to others here. What I realized is that I have owned PC games from all the years 1988-2008, except for 2001-2002 (maybe I'll buy Hostile Waters and Original War to fill in the gap). I also realized that I have lost, gotten rid of, or given away a number of good games and there are many that I never finished. Note that this list doesn't include all the PC games that I've played on someone else's computer or via illegitimate copies, nor does it include any of the multitude of shareware, demo or trial versions of games I've played. I'm also sure that there are a few games I've forgotten about.
Legend:
B - Bundled
C - Currently Playing
G - Given Away
L - Lost
O - GOG.com
U - Unfinished
W - Played using WINE
Purchased
King's Quest IV (1988, L, U)
Sim City (1989, L)
LHX Attack Chopper (1990, L, U)
Sorcerian (1990, L)
Stellar 7 (1991, B, L, U)
Commanche Maximum Overkill (1992, U)
King's Quest VI (1992, B, U)
7th Guest (1993)
Myst (1993, U)
Shadowcaster (1993, L, U)
Star Wars: Rebel Assault (1993, L)
Cyberia (1994, L)
System Shock (1994, U)
Crusader: No Remorse (1995, C, U)
Descent (1995, L, U)
EF2000 (1995, B, U)
MechWarrior 2 (1995, B, U)
Warcraft II (1995, U)
Whiplash (1995, B)
Wing Commander 4 (1995)
Hyperblade (1996, B)
Quake (1996)
Silent Thunder: A-10 Tank Killer II (1996, G, U)
Diablo (1997)
Heavy Gear (1997, G, U)
NHL 98 (1997)
Quake Mission Pack No 1: Scourge of Armagon (1997)
Quake II (1997)
Grim Fandango (1998, U)
Half-Life (1998, L, U)
Motocross Madness (1998, L)
Speed Busters (1998, B, U)
Aliens versus Predator (1999, L, U)
Kingpin: Life of Crime (1999, B, U)
Deus Ex (2000)
Giants: Citizen Kabuto (2000, C, O, W)
MDK2 (2000, C, O, W)
Sacrifice (2000, C, O, W)
Tony Hawk Pro Skater 2 (2000, U)
Call of Duty (2003, W)
Grand Theft Auto: Vice City (2003, U, W)
FarCry (2004, U, W)
Half-Life 2 (2004, W)
Darwinia (2005)
FlatOut (2005, W)
Half-Life 2: Episode 1 (2006, W)
Prey (2006, W)
Tomb Raider: Legend (2006, W)
The Orange Box (2007, C, W)
Audiosurf (2008, W)
Borrowed/Given
Doom (1993)
IndyCar Racing (1993, U)
Ultrabots (1993, U)
Wing Commander: Privateer (1993, U)
TIE Fighter (1994)
Doom II (1994)
Fleet Defender (1994, G, U)
Duke Nukem 3D (1996)
Hope that wasn't too long :)

Oh man, your list is quite small for 20 years :D

QFT

Ooh, LHX Attack Chopper. I have the Sega Genesis version of that game.
You only borrowed DOOM? That's the only PC game that everybody must own.

I only own DOOM on XBLA..
THIS.

There's no way I can list all the games.
I literally have lilke four cd spindles of old games along with a closest full of old boxes/cd cases, etc.
I started pc gaming in the early 90's (started console gaming first with the atari/nes/sega) and still game on both.
Some of my first pc gaming purchases were Lords of the Realm, sam and max, monkey island, Lands of Lore, and Interstate 76.

Hang on to those Monkey Islands. I recently thought about nabbing 'em off of eBay, and was quite shocked by the high prices. For being such popular games in their time, they surely seem to be rare/expensive.

Nice list, glad to see 7th guest on there!

No one ever finshed Kings Quest. I'm sure it was actually impossible... Love to have a go now that I understand gaming a lot more, but I can't find it. Still, good times trying my best to complete that game...

I'm not sure what you mean, I finish the games quite regularly and originally without any hints. I used to speed run the original.

Everyone should know that it is not the size but the quality... :D