Microsoft Virtual PC is a great idea. I'm intrigued by the virtualization technology. I've been pushing it hard at work (we have far too many "development" and "testing" machines which could be easily virtualized). And a found a use for it at my favorite small business client, wrapping old DOS-based applications for continued use under Windows XP. (VMWare is great too -- MS VPC is probably better for Windows-centric shops). And the 45 day free trial makes it an easy sell.
But boy is it hard to do the basics, like get a bootable Windows 98 system. Track down this CD, that bootable floppy, figure out how to make floppy images, etc.
Don't make it so hard to buy and effectively use your software. Let me "unlock" bootable images of DOS 6, Windows 95, Windows 98 from your website with my license key or original CD. Right now, you need to be a real geek and a packrat to get this working. After an afternoon, I'm still only halfway there. This could be a big advantage over VMWare (can't do the same due to licensing). And frankly, a little abuse/piracy of ancient software is harmless (the going price for licenses is about $5 on Ebay).