Smallest possible windows that can run office 2010

[itix]

Hey! Maybe there is a better area for this question, but I am definitely unsure where to post!

I need the smallest possible 64 bit windows (in terms of drive space) that is able to run office 2010. According to this table, windows 7 and server 2008 seem to be able to run it but I am not sure... thought to ask here since I suppose that you guys know this kind of stuff.

Right now I am running a windows 7 (that the machine was bought with) and Linux dual boot and I am not happy about the huge 30 gb chunk windows 7 has eaten out of my hard drive even after I stripped it of all the add on programs it came installed with.

If 7 and server 2008 are the only 64 bit versions available, is it possible to install a 32 bit windows on a 64 bit machine?

I know that it is with Linux but but I am unsure with windows. XP-nlited should take a lot less drive space but I have an SSD in my machine... guess you need a SATA version of XP in that case.

Any thoughts? Thanks :)