When I asked Gabe this very question, here is his response:
Not for gameplay, although it would help if you are running a bunch of big demos back to back. Our demo machines at E3 had a gig so we could run through the demo sequence without ever hitting the hard drive.
-----Original Message-----
From: Sean [mailto:
Sent: Wednesday, September 17, 2003 8:46 PM
To: Gabe Newell
Subject: RAM Question
I know you're busy so I'll try to be fast. I was wondering if there's much of a performance difference in HL2 between having 512MB of RAM and 768 - 1Gig. Thanks for your time! And by the way, that was really cool of you guys to let that kid tour your place. Hats off to you. Thanks!