Ahhh, thanks for that, I see now.
I don't think updating WinAMP will change it, that's how playlists are supposed to behave with a relative path instead of an absolute one, I'd just forgotten about that behaviour, thanks for picking it up for me!
Spaces aren't necessarily Unicode, they can be represented in the standard ASCII set. I mentioned Unicode because any paths in the playlist that ARE Unicode will always cause Audiosurf to crash at the moment.
I'll update my code anyway with the relative paths so those playlists will work in the next release, although that in itself isn't worth another release right now I don't think. I'll wait for Dylan to fix the Unicode path problem and release another version then, as I know it will require some changes to be made.