Virtual PC and changing serial code

So - I've been Windows for years and run a network of 10 XP and W2k computers. All works fine - I know the quirks of Windows but it's fine. My Dell Latitude notebook is tried and tested and a real workhorse, so all is great.

Still - the ibooks and powerbooks are too damned sexy to ignore so I got one of each to try out. It's going ok. Some mac quirks wind me up, like Intuit's online quickbooks doesn't work at all on the mac! - but it does in virtual pc.

Herein lies the issue. I went through installing the books side by side but stuffed up when it came to installing Virtual PC (6). I've got two boxes of software but used the same install disk and just changed the serial number for each. I installed 6.1 and then ran the update 6.1.1? Anyway - all was good...but I goofed. Despite having two codes in front of me, I appear to have used the same install code for both versions. What's this mean? Virtual PC detects another version is on the network with the same serial number and they both halt until one is shutdown.

Not a problem - I'll uninstall and start again with the new number right? WRONG! Nothing I can do, and I mean NOTHING) can get me to the window to reenter the serial number or change it to the unused one I have. Any ideas? I need to remove every trace of the installation so I can reinstall from the start again.

Any ideas? Help!

tim