Want to learn from my mistakes? Here we go.
First of all, resist the urge to import your Windows machine into VMWare. Unless it's chock full of software you've paid for and that needs to phone home to work, instead I recommend you simply start from scratch.
Case in point: I imported my XP Media Edition machine. Footprint was 70 gigs! And it refused to compact via VMWare tools. It would peg my dual-core AMD machine after running for an hour or so.
I finally blew it away and started over.
I now run XP Pro and my processor usage remains minimal. The machine's footprint, with Dreamweaver MX, Quicken 2006, Paint Shop Pro 7, and Open Office is 4.4 gigs.
Don't have a serial number? All I can say is use your imagination. I did, and worked around it legally, though Microsoft might quibble over the details. Let's just say that if a machine that was licensed for XP Pro NEVER USED it, my conscience is just as clean as it would be in importing a physical machine into VMWare that will no longer have Windows as its OS.
However, don't overlook another easy solution: Windows 2000.
I have yet to find an XP-written app that won't run on Windows 2000. In fact, my Epson software that came with my CX7000 all-in-one simply won't play ball with XP. But I scanned a big pile of family photos yesterday through my Windows 2000 machine.
Its footprint is smaller, too. The same equipped machine running Win2k has a footprint of 3.6 gigs.
And NO Microsoft activation!
So if you have Windows apps you simply MUST use, consider a VMWare install of Windows 2000. It ain't pretty, but it's a proven workhorse that gets the job done.