In reply to cliffanger: Depends what your requirements are, especially if you need any specialty software. Unless you enjoy fiddling with computers, I wouldn't bother getting a mac and then trying to run windows-only software on it (using Boot Camp, Virtual Box, VMware or Parallels): it's perfectly possible to do so but always needs a bit of setting up and it can be fiddly to use at times. Not the easy mac OSX experience...
If you just want a box for email, t'internet and general stuff the mac is likely to be easy to set up, use, and not need a lot of upkeep by comparison to the PCs, which habitually needs antivirus updates on a daily+ basis anyway.
When you say files, what do you mean? Excel-type databases, documents, accounts packages, or something else? OpenOffice will run on either PC, mac, or anything else and not cost anything, but is less polished than MS Office still which remains the industry standard. The Mac version (iWork) looks very nice - and KeyNote is (for me) much better than Powerpoint - but is generally still style over substance for 'serious' use. But then if you want easy, smart looking invoices or whatever it may be just what you need.
Given your phrasing of the original question I would keep well away from Linux
HTH
B