I'm running my Coolscan 5000 on Windows 7 using Nikon Scan. If I recall correctly, I installed the version for Vista that supports both 32 bit and 64 bit versions. Nikon mentions somewhere on their website that they tested that version of Nikon Scan on Windows 7 and it run fine, but they cannot guarantee that all functions work i.e. Windows 7 is not officially supported.
Windows 7 works fine for me except for one thing. That is that unless you do a bit of a workaround ICE does not work. The workaround is to first preview scan all images to be scanned with ICE turned on, and then main scan those images with ICE turned on. ICE needs to be turned on for both preview scans and main scans. If you don't do a preview scan with ICE turned on, scanning will end in an error.