I can’t think of any problems. There’s a lot of help on user forums. She sent me a document she wrong using Open Office and it had a strange font when I opened it on Windows (also using Open Office). That’s the only weird thing that’s happened.
Some video content doesn’t work properly, but most does. Programs written for Windows won’t run, obviously. The Eee PC is pretty limited, so you shouldn’t expect to load it up with software applications anyway. It’s a great mobile platform because it’s light, durable and cheap.
If you just want to use if for web stuff and basic office applications it works great.