The only real difference between the Home Premium and Professional editions is the Windows XP mode.
Here is a link comparing the different editions:
http://www.microsoft.com/windows/windows-7/compare/default.aspxThe Home Edition is the more economical version ($80 lower). If you don't need the Windows XP mode then the Home Premium is the logical choice.
I have the Ultimate edition for the multi-language capabilities. My wife is Japanese and the Windows program is in full Japanese language mode on her computer. The only thing I can understand are the icons - all the text is in Hiragana/Katakana/Kanji.
Just make sure you use the 64-bit versions.