Tablets typically won't give you enough on-board storage for all your files. But in today's cloud-based world, that's not a problem, because cloud services such as Google Docs, Dropbox, Box.Net, Evernote, and SugarSync give you plenty of storage. If you go that route, an even better bet is to use tools that manage multiple cloud-based services. Check out my blog post "5 great free tools to manage all your cloud storage" for all the details. ZeroPC is a favorite as are doo, hojoki, Primadesk, and the Chrome extension Cloud Save.
Tap remotely into your PC
It's not likely that you'll be able to give up your PC forever. So you'll want to be able to tap into it via remote control software. There are some excellent free choices out there for iOS and Android tablets, including TeamViewer, Chrome Remote Desktop, Splashtop Remote Desktop, and VNC. For fuller reviews, see 5 free alternatives to LogMeIn.