I have used Windows 7 Beta for about a year now and have had great success. I have also been able to run other windows applications that would not run or run well in Vista. I think Microsoft got it right this time.
As far as 6.0, the program seems to run fine. I use this particular installation for development only. The program runs faster and I have not seen a crash.
For any critical application, you might want to wait for the NI blessing. Otherwise, I would have a backup running on another machine with an earlier Windows version ready to go.
Lookout 6.2 display clients are definitetly more robust on Windows 7 x64 machines. I assume server processes would also be fine.