Digital BW, The Print

Firstly, many thanks to all those who took the time and trouble to 
answer my previous questions.  Your help and expertise is very much 
appreciated.

I have to upgrade my computer.  Here in Israel, it seems that the 
vast majority of people that I know use Windows.  Is there a really 
good reason to use Mac over Windows XP for Photoshop and printing on 
the 2100?  I hope not.

Second.  Given that Windows is on a par with Mac, what would be an 
ideal spec for a fast Windows machine.
Thanks in advance
Yaakov Asher Sinclair