I am running CS5 and LR 3 on Vista 64-bit but am building a new Win7 PC. Can I upgrade both CS and LR to the new machine OS without starting over with expensive full installs?
You should be able to deactive you software on your old computer then reinstall it on your new one. Just make sure you have the serial numbers to activate it.
And just to add: You are wise to be building the new system with Windows 7.