Depending on the modes you want to operate, you might already have what you need. I suspect digital modes (using DM780) would be the easiest as the remote desktop (aka microsoft terminal services) will let you remotely control the PC just as if you were sitting there. You usually have to enable remote desktop connections on the "receiving" PC with the radio and then just run the client from the "sending" PC. I do this by running "mstsc", but then I'm a computer geek, so there might be an icon you can click somewhere.
If you want to do voice, you would need a way to get the audio back and forth. I know some people have done it... here is one web site with a little info about it: http://www.norcalmfg.com/amateur_radio_stuff
This is a buddy down the road. His radio is in a detached garage near the antenna, and he works it from the kitchen table in the house.