Just as an example, I went for Pro over Home Premium since I wanted XP mode. Thus far I haven't had a need for it, but you never know.
True, but you can always run it via VM (ie VirtualBox,etc). If you have software that doesn't run correctly on Win 7, you are better off getting new/upgraded software.
I went with Pro because I got it free via MSDNAA and MSDN and the school book store only sells Pro for $50-60 (or so, cant remember exact cost, but it was less than $110) .
Fair enough. I just went with XP Mode because it integrates so well with the rest of the OS. Running XP and 7 applications side-by-side is extremely cool.