I was a late-comer to Gabriel Knight, but I used to play the Windows CD version of GK1 about 4 years ago, and I used an on-line patch to install it on modern computers. It's been a few years since I've played, and I no longer have access to my CD, so I downloaded the game from GoG... and the opening credit music is different!

I'm POSITIVE this isn't my poor memory... The menu and titles music were different. But my GoG version seems to play the same musical cue twice (during the menu before the dream, and during the credits sequence after the dream). The version I used to play had a different, pounding rhythm over the opening titles.

Anyone have any idea what the difference is in these copies? To be honest, I much preferred the opening song from the version I used to play, as it pumped me up.

You're right, the opening credit music is different. While an old version apparently used the closing theme at this point, the new version just repeats the main theme from the menu.

"Lets play" video of the current version (opening and 10 min. gameplay):
http://www.youtube.com/watch?v=L5LwDCjVjfI

Different opening credit music:
http://www.youtube.com/watch?v=CsBC4E3aEMQ

Equals to end credits (slight SPOILER, not story wise but, well, it's the end credits)
http://www.youtube.com/watch?v=uMPVIkUUmlA

It's not clear, when or why they changed it. It could also be, that this is different because of regional versions (e.g. UK vs. US)