Have you tried checking the Blizzard support site or forums? I actually have issues with the downloaded version of Starcraft I tried installing a few weeks ago but haven't taken the time to resolve them yet (I know the disc is somewhere but damned if I could find it right now). A quick glance at their support site at least offered me some stuff to try when I find the inclination. I know they'll probably have nothing about running it in Wine, but they may have some fixes for your XP issue.