I have two problems with this game. First is that I can only play it through LOADER.EXE, when I try to play using start.exe I get to see the intro and the menu, but nothing happens when i press the New Game-button. Secondly, the music is all messed up. Sounds like it constantly jumps from different positions in the song. Any help?

Got the same problem, music sounds awful (gets louder / softer, jumps).
Menues are also too fast (check the encyclopedia).
CPU slowdown tools won't help, sadly.

Yeah, same here. The music is messed up, sounds like it is jumping constantly forward and clipping. I have an integrated Realtek HD Audio as a soundcard, if that helps any. It's kind of annoying. Any suggestions?
Edit: I tried downloading that bink video/audio-codec (whatever it is) but don't know or if it needs to be configured somehow. But so far, no effect.

That did work for me! But now my menus turned really really laggy.

I had the same problem, your solution is working! Thanks a lot!

Yay! Now it works like a charm! Thanks a lot, bro!

If I set it to basic, music plays fine but I get messed sounds :( My card is Soundblaster Audigy 2ZS.

Is there a way to do this on a per-application basis? I play some games where I'd certainly want the acceleration to be all the way up, and having to alter this setting every time I want to play OutCast, and then change it back, is kind of a pain.

Yeah I would like to figure this out too. Some games have problems with sound accel, for example Fallout 1 and 2 also, and it really sucks having to adapt it all the time.

Will there be a fix for this other than having to change Sound Acceleration rate every time one wants to play the game and then back again afterward?

If you've got a SBLive! card then you can use the ALchemy program to fix sound acceleration problems on Windows 7 & Vista
I used it to fix Fallout 3's radio on Windows 7 64bit, so it may work with Outcast. Works well with Outcast era games like Thief too.

If I put the sound accelerator down to standard, as suggested, I still get the music skipping and changing it's volume. To avoid the skipping etc, I have to turn the sound down to basic, but by doing that I lose 3D sounds/sounds from my rear speakers.

This leaves me with a choice of the music being okay but only from the front two speakers or have it skipping etc through 4 speakers.

I have never had a problem with any of my previous GOG games, but as it is, I feel Outcast is still 'broken'.

Thank you!! That fixed it for me too! For two speakers at least.

I don't have the "3D sound" option it seems, though I have "EAX", but I don't think its on even if its marked on. I don't have any soundblaster though, just a built-in Realtek (USB) audio thing.

EDIT: Never mind, I just found out that the 3D option disappear when sound hw is set to below "standard" in dxdiag. If set to "standard" or higher it is present, but the music skips again... IE the same as UK_John reports above.