screw everything you need to have half a terabit of storage humming away on your desk here, mmmm toasty.
You could build a working pc out of bits and have probably:-
cheapo case (postage will cost more than the case!)
basic motherboard with some form of sound probably only support an agp card aswell but you won't need it.
2x 128mb sticks of ram probably really slow stuff
1x cd writer
40gb HD, this might be the most expensive part, as most people keep HD's till they die, worth going for a near new/new one here.
windows, also fricking expensive.
power unit, if you are lucky you might get one with the case, probably about 250-3??w but its not like you are running massive power.
amd 3000+ or somthing like that, can be overclocked quite nicely to give a decent 2.4 or 2.66ghz or a base level celeron may be worth a look
usb card (might be on case, or it might be on motherboard, but chances are not)
all cables will probably be with power source and a connecting cable will be about £1
forgot to say you could build a good working pc ready for broadband for £100 not inc monitor, any sort of graphics card (don't bother buying anything cheap unless you like mrs pacman rather a lot) or pheriphals