If you want to get your hands on a piece of software history and are quite keen Windows Vista you might want to get your hands on the "Microsoft Windows Vista Ultimate UPGRADE Limited Numbered Signature Edition".
Let's gloss over the fact that the length of the name is completely ridiculous and the fact I would never personally buy a copy and see it for what it is - a piece of digital history.
There are 20,000 of these copies to be had and they may well be worth a few £££ seeing though it's Bill's swan song etc.
You can get your copy from Amazon.
I have a copy. There are actually 25000. For $10 more than the regular upgrade, it was worth it.
I think that was $10 well invested, Fred. :-) See you on eBay in 10 years!