Hi, Alan.
No problem!
Like Hank, I've been installing successive versions of Quicken on successive versions of Windows since 1990. For over five years, I've been dual-booting multiple Windows versions. (I now have 32-bit WinXP on F: and 64-bit Vista beta on J:, for example.) But no matter where my operating system is installed, I always install Quicken into E:\QuickenW. That way, I can boot into WinXP in the morning and run Quicken to record some checks. Then I can reboot into Vista in the afternoon and see that my check register already includes those checks. No matter which operating system is running, my data files are always in E:\QuickenW, too, with Quicken's automatic backups in E\QuickenW\Backup and my manual backups in a couple of locations on other hard drives and CDs.
I've installed Quicken so many times that I should have the installation screens memorized, but I don't. But early on, it asks if you want to do a "typical" install or a "custom" install. If you choose "custom", you can choose where to install Quicken. The default, of course, is C:\Program Files\ Quicken (or QuickenW), but you can either type in or browse to any folder on any drive in your computer. Quicken doesn't really care; the default shown is only a suggestion.
After Quicken is installed and running, you can change the location of your data files easily. Perhaps the easiest is to use Quicken's File | Copy command to save your fileset (QDATA.qdf plus the related QDATA.* files) in your chosen new location. Then use File | Open to load that copy and work with it. When you close Quicken, it will save the current version of your file to that location. And that will be the default location each time you start Quicken - until you change it.
RC