Back up for home network on Windows 7

I have upgraded my computer (so that I do not have to wait days while HMRC PDFs files load) using windows 7 Prof.  I have my computer home networked to another computer. Windows back up does notrecognise the network for back up.  I am looking for software that will back up folders from my PC and the other computer thru the network onto external hard drive, for either free or reasonable price. All the software I look at currently either a) does not allow back up thru the network from the other computer or b) does not allow a "set" to be made up so that I do not have to choose folders everytime I back up, or isa silly price.

Any ideas gratefully received :-)

Iain