windows 7 32 bit or windows 7 64 bit ?
It very much depends on your setup. To my knowledge (and please let me know if I am wrong), the 32bit Windows 7 os can only utilize 2.5 gigabytes of RAM. If you have, or plan to upgrade past this amount, it's smarter to install the 64bit version. However, if you have a smaller form system, or just plan on using a browser and non-resource heavy programs, 32bit would be just fine.
I run 64bit, purely for the fact that I have an i3 with 4gb of RAM.
Hope that helps