I did try it. Sorry I didn't make that clear.
The Setup program refuses to install unless you have "at least Vista"
If you know a way to fool the install program - I will try it.
I'd enter a complaint on the Adobe Forums, and monitor them for any work around. There are still a large number of people using XP. Windows Vista was much worse than XP, but windows 7 64 bit is a pleasure to use with resource hogs like photoshop and lightroom. It is a much more pleasant experience when a new install is run as long as your pc is not too old, all the drivers are there, or are automatically downlooaded for most common hardware. I did have to install my Epson 3880 driver from the epson site, buts all the other hardware worked fine.
Since I have moved to SSD for boot drives, Windows 7 handles them better than XT or Vista as well.