Another (admittedly minor) difference:
If you're upgrading from Windows Vista Home (Basic/Premium) or Vista Ultimate to Windows 7 Professional, you'll need to perform a full, clean install.
I had Vista Home Premium installed on my laptop and upgraded in place to Win7 Home then paid for the upgrade to Win 7 Ultimate. Had no issues during this process.
I have HP Pavilion Laptop and HP sent two discs, one was a prep disc and the other Win 7 upgrade disc.
The prep updated drivers, certain HP software and a full Bios Update.
Price of Win 7:
On the site and in stores Win 7 Pro Upgrade is listed around $200.00 and Ultimate at $220.00.
I chose to buy the upgrade via Windows anytime upgrade and the price I was quoted was $90 for Win 7 Pro and 140.00 for Win 7 Ultimate. Since I was expecting 220.00 I just went ahead and purchased the ultimate version after the Win 7 Home Premium upgrade from Vista. I feel I saved quite a bit and got a great deal.
I have NO idea if that is the normal upgrade price through anytime download purchase or special running when I purchased.
I did NOT get a disc, I did print out my receipt. If something happens and I have to reinstall win 7 I do not know if I can redownload Win 7 Ultimate again.
There are small differences between Ultimate and Pro, minor tweaks and all features unlocked.
I do NOT know if Win 7 Pro has this ability or not. System Restore saves archive versions of your files, you can right click on a file and select properties. A new tab is available called "previous versions" that finds all previous versions of that file in both system restore points AND full /partial backup archives on the current drives AND if you plug a usb or firewire hard disk or external drive that also has full or partial backups it will search those as well to find all previous versions of files.
I never tried Win 7 Pro, I was going to purchase that but when I saw the price I was given for both I just went ahead with Ultimate.
It depends on what you are going to be using the computer for.
I do a lot of web design, programming, writing, major multi-tasking, win xp mode, skype, video, audio etc...
I switched over to my laptop with Win7 Ultimate as my main computer now because it is so much easier to work in than XP and 99% of the software I use works in it and what doesn't works in XP Mode.
I did the upgrade over Vista so it brought in all my files and registry settings from Vista, including all the extra junk and clutter. Few things don't work due to some sort of a corruption but I never use those software so I don't care. The benefit of not having to reinstall all my software and have all my settings ported was too much of a value to me than wasting time on clean install procedure. Others do things differently though.
I did notice that things that did NOT work in vista now work in Win 7 such as my System Restore feature works instantly now, it was corrupted some how in Vista.
Which should you get and is the price difference worth it to go from Pro to Ultimate?
Depends on what you are doing with the computer AND if you want ALL features unlocked or not.
From the comparison list they have on the site there is only two things it shows as benefit, Language Pack and Encryption.
There are other very small differences but they don't have them listed anywhere.
I can only compare myself from Vista Home Premium to Win 7 Ultimate and 7 Ultimate has features Vista HP doesn't. I am not talking about the win7 features like auto docking and expanding / compare windows, window shake etc etc...
Toss a coin I guess, you know that Microsoft cripples the tiered versions 7 basic doesn't have all features of 7 Home and 7 home doesn't have all features of 7 Pro etc... The only thing above Ultimate is Enterprise version and for a normal user you don't need or want features of that version plus it doesn't come with Windows Media Center, Ultimate Does.
Hope I helped you.