You can't run Windows programs in OSX - you need to either dual boot Windows (using Boot Camp) or set up a virtual machine). Documents such as Word docs should be fine as long as you have a program that will read them - e.g. Office 2011 or LibreOffice.

To answer your question - if I had 2500 dollars (or pounds) in cash, I'd buy a Mac Book Pro (13") and a new pram.