My understanding is that right now the Facetime software only runs on iOS devices and Macs, so if you're using a Windows machine, then I don't think Facetime will work.
But, from what I've heard, Yahoo Messenger has a chat client for the iPhone and for Windows that allows video conferencing, but the Mac client does not yet support video. So that should be a potential solution. It's also likely that any of the potential solutions will require you to be using Wifi, rather than 3G/Edge data. Although this article mentions Yahoo working over 3G:
http://www.cultofmac.com/yahoo-messe...s-review/63074