The biggest difference between Home and Professional that *I* found important is that Pro allowed me to download Windows Virtual PC from Microsoft. What does that do? That allows me to run Windows XP if I need it. That's a HUGE security blanket in my world.

It came in handy because I thought I needed to install my full version Photoshop 7 before I used my CS2 upgrade. Windows 7 wouldn't install PS7, though. A quick pair of downloads later and look at that -- I have a window running Windows XP and it's installing my PS7! (Turns out I didn't need to install PS7 first; just putting the disk in the DVD drive was sufficient but I didn't know that at the time.) Now I can revert to XP whenever I need. So if I *do* run into anything sticky, I can solve it. Or, so I hope.

Win7 Pro has some other features but those don't mean a lot for me with my very simple set-up. If you have a home network to back up to (a server, I assume) or log-in from home to a work server, it has some enhanced features. The 64-bit version is only worth it if you're getting one of the dual or quad core machines. It is supposed to be faster; I have no proof of this. I am constantly impressed by me new system but I'm upgrading from a 10 year old computer so I may not be an unbiased judge.

Since you're thinking of purchasing a new computer, you'll probably be buying at least a dual core and so the choice between the two will probably already be made for you. :)