I agree with mastercomputers that M$ is mainstream.On nearly every office pc has the M$ office products.But we -who doesn't use computer for commercial purposes-are using both. First of all OpenOffice is free and easy to obtain.Most of the people i know in the university can not afford M$ Officeand usually use OpenOffice in their own pc.
I am using a homebuilt External Hard drive (usb 2.0) 80 gigs for backing up my movies and exchange them with my friends.First I used for second os Suse 9.1 but from Usb it was unreilable.Virtual Pc is rather slow and consuming the pc cpu power so much.I recommend install a new hdd for a second os (Dual Boot or Tripple )
It is really very hard to say "this is the best" It depends on your needs. I am still using "f-prot" dos version. First of all are you going use a free one? Or are you going to pay for an anti-virus program? ooops i didn't see the attached picture!