If you use SCUMM Revisited 2
, you can delve into Grim Fandango's resource files and extract them, which of course encompassed both the sound and the artwork. The only problem with this is that the music files included with Grim Fandango are actually of notably inferior quality to those on the soundtrack. That is, they are compressed to fit on two CDs amongst everything else, and as such the sound quality does take a hit.
This is wholly unnoticable while playing the game, but if you're casually listening to them via Winamp or something and play the rip and the soundtrack versions side by side, you will notice the ripped versions sound significantly less clear.
Still, having those files is better than not having them, and unless you're using headphones you may not be able to tell the difference. However, be aware that there will be a quality distinction between the rips and the OST. If not having every single cue doesn't bother you and you do care a lot about sound quality, simply listening to the OST probably makes for a better experience. The rips tend to have lots of ten second tracks and such, you see, and they aren't looped.