There are far better solutions for a torrent server, I use a atom powered netbook as my torrent server, switched on 24/7.
Measures around 18w when working hard, less most of the time, it also acts as a media server through Opera Unite, as well as a Print Server and USB Device server.
I got it for free, the screen is broken, I have removed the screen completely, its just the base, I access it via VNC from my Main PC when I need to, all drives and printers are mapped already on PC's and Laptops across house.
It runs Linux Mint, so very very easy to set up. 1.6Ghz single core. 1GB ram, 250GB Hdd (upgraded the 80Gb one in it) 1TB External USB HDD Permanently attached (it spins down correctly after 30Mins non use)
Just like this, minus the screen, its compact and honestly uses so little power I do not care if its left on!http://cgi.ebay.co.uk/ACER-ZG5-NETBOOK-LAPTOP-INTEL-ATOM-1-5GB-RAM-160GB-HD-/290565158163?pt=UK_Computing_Laptops_EH&hash=item43a7087513