wire the external harddrive to the pc power supply.
check the adapter output voltage with a multimeter first.
Well my ups shows my screen comes in today now I need to pick out a pc.So what do you think about this one.http://cgi.ebay.com/ws/eBayISAPI.dll...tab%3DWatching
Also what is the best way to power external hard drives I have 2 500gb seagates I am going to install.What do you suggest to power it. Just a standered power inverter? How big?