You should be able to use your router with the Mac.
Your files need some thought though. The Mac book will come with iLife (Photo, Music Creation, Movie, DVD production) plus Mail, Calendar, Contacts, Text editing, iTunes and Safari as a browser. Text edit will open and save Word files (.doc, .docx) but there is no software to open the rest of the office suite (Excel, Powerpoint etc.) You would have to buy either Office2008 for the Mac (£100+), OpenOffice (Free) or Apples own suite iWork (£69). I use iWork most of the time. Photos transfer pretty well. So does your music. iTunes deals with most formats. If your music is saved as .wmv files then you can get Windows Media Player for the mac. In the case where programmes exist only on the PC, then there are generally Mac programmes that can open and save these formats. If you can give us some idea of what programmes you use on your PC then we can give you some ideas. The Apple site has advice on how to do this. Go to
http://www.apple.com/uk/mac/ and go down the page to the "Find out how" section and click Move to Mac to begin