Dunno about 03 but I recently installed Office XP (2002) almost without pb on a Windows 7 64bits. The only pb was with the companion help API that doesn't exist anymore on Vista/7 but is downloadable as a hotfix from Microsoft.

So I'm perplex about the need of a VM to run Excel 03 and won't debate about the use of it to generate code as anyone have different habits for his workflow.