Well it shouldn't need DOS, as this game was designed for Windows 9x. It WILL run in XP and 2000, you just may need to play with it a bit (XP... as 2k runs it fine for me).
Make sure you've got the disc in the drive, no cd cracks, and it's clean.
I guess you need to check Yoda's Help Desk on LucasArts.com support pages. :P