What do you want to do?
Transfer a file? Some file explorers on android (ES? Astro?) offer Samba functionality. Then there's Dropbox and google docs which synchronize between PC and Android.
Remote desktop? I'm always fond of LogMeIn Ignition, but it might be a bit on the expensive side. However, it just works, which can't always be said of the various RDP applications out there.
If you use Linux on your PC, you could also use SSH from Android.