I have just bought a new machine with an i7-620M processor and Windows 7 Professional 64 bit with XP mode. I also have Office 2010 Home and Business. I will be running Adobe Creative Suite 4 Design Premium CS4 and need to know if I should run 2010 Office in 32 bit and will CS4 run on the XP mode?
Running office in 64-bit mode won't gain you a lot. Also, if there are any other additional plugs that integrate with Office, they HAVE to be 64-bit. If they are 32-bit, then it won't work. Mostly, this might come to things like Anti-virus software that uses plugins to Outlook for Anti-spam, etc.
As for CS4, that looks like it's supported under Windows 7. Whether it runs in 32 or 64 bit shouldn't be a problem unless they do something strange that won't allow it to run under 64-bit Windows 7.
If it won't work under Windows 7 directory, then by all means, try it in XP mode. You can't hurt anything by trying.
I run Windows 7 64-bit professional, but I run the 32-bit version of Office. There really wasn't any gain to running the 64-bit version at all.