I believe their are wireless devices you can connect to VGA/DVI/HDMI ports on the PC that will transmit the signal wirelessly to another device which you can connect to your HDTV. I've had a few PC's hooked up to my LCD and it was fun. I have often contemplated doing this some more and may now just run my incoming laptop through it, but my issue is finding the right components, cables to run sound through the speakers.
Even if you have to run cables to the HDTV I feel video is the easier aspect of a PC on HDTV concept. Wireless mouse keyboard worked for me like a charm in the past.
Run some searches... see what comes up. Google my friend.
Something like this maybe: http://www.cnet.com.au/dvdpvr/0,239035801,339285006,00.htm
I've seen other similar products. With the right adapters and product, I am pretty confident it is doable.
Best of luck!