Oldest originals I have are Robocop & Batman The Movie for C64.

Oh good god! I never threw any game I ever got away so this list is just off the top of my head and no particular order:

TI Invaders
TI Pong
TI Astroids
Under A Killing Moon
Full Throttle
Day of the Tentacle
Grim Fandango
Space Quest 1-6
Realms of Arkania 1
Voyer (I know I know!)
Virtual Murder: The Magic Death
Radio Active (I got this at a store years ago while I was participating at a Science Fair)
Quake 1
X-Wing vs TIE Fighter
Vampire the Masquerade - Redemption
Star Wars: Dark Forces 2 - Jedi Knight
Jedi Knight: Mysteries of the Sith
Jedi Knight 2: Jedi Outcast
Jedi Academy
Dune
Test Drive
Dust: Tale of the Wired West
Leisure Suit Larry (all the originals)
Wing Commander IV
Journeyman Project 1
Journeyman Project 2: Buried in Time
Journeyman Project 3: Legacy of Time
Ghostbusters 2 The Game (I know...)
Ultima 4 (though I played through them all)
Zork 1-3
Zork Nemesis
The 7th Guest
Schism
Myst
Riven
The Time Machine

There are probably more I'm not thinking of, but again that's off the top of my head. My father got me started at gaming since age 2 (subsequently programming at age 3, TI BASIC, but hey at 3 that isn't bad), and it's been a life long hobby.

The only boxes i kept are:

Star Wars: X-Wing CD-ROM Edition
Star Wars: TIE-Fighter CD-ROM Edition
Star Wars: Dark Forces
Star Wars: X-Wing vs. TIE-Fighter
Battle Isle: Incubation
and two LucasArts Adventure Collections

And yes I was a Star Wars fan before Episode I happened...

Of my floppy disk games, I have boxed versions (with manuals) of:

Quest for Glory 1 VGA
Quest for Glory 2
Quest for Glory 3
Space Quest 1 VGA
Conquest of the Longbow
Lure of the Temptress
Ultima VII (lost my cloth map though, am still devastated)