Bill's fan club will probably hate me for this, but it has to be said:
1) Download a Linux Distro
2) Burn to CD/DVD (Mandriva Free is a DVD ISO)
3) Insert CD in CD drive
5) When prompted, say "Yes, I do want to reformat my HDD"
Of course, it's not quite as simple as that. You'll probably want to backup your documents first. And in between steps 4 and 5:
4a) Realise your computer has ignored your CD and is starting to boot Windows.
4b) Reboot again
4c) Hit Delete like a mad thing to get into your BIOS
4d) Spend a merry 5 minutes working out where they've hidden the boot order screens.
4e) Amend your boot order.
4f) Press F10 (usually corresponds to save and exit)
4g) Wait for the computer to reboot and start loading the CD
4h) If it's a Live distro, double check that most of your hardware still works.
4i) Double click the button to install it to your computer.
But I'm not surprised at the Microsoft employee admitting they're not entirely sure of the dependencies any more. What almost certainly happens when they're building a new version of Windows is to start with the existing version, then change / tweak bits as needed. And if the programmers don't document their code fully, then seek alternative employment, you're screwed. Heck, there's probably still some Win 95-era code hiding in Win 7... and maybe the occasional method or two from Win 3 or earlier...