I use win 7 for Internet explored and that's it (via parallels) mostly for sites that utilize active x controls....I had a copy I got throguh student pricing for like $30 so for me it was worth it....other than watching my son via full screen on IE, there is not much other use for it, for me.....works great and boots fast....
why take up the extra space when I would really not have any 'specific' use for it, per say.
Why ask which version of windows to buy then?
Personally, I prefer using windows under vmware as opposed to boot camp because I get keep using OSX and I can quickly jump over to windows when I need too. The advantage of bootcamp is windows gets direct access to the hardware, which helps games and other apps that need that access.