Errrr, you’re looking at spending the best part of £200 on a pretty low spec 2nd hand box… WTF for?!?!
If it was £20-30, fine, no problems… For WELL under £200 excluding an OS (and you can just install Ubuntu for free if it’s only to stream iPlayer etc.), look at the following…
http://www.ebuyer.com/251310-zoostorm-desktop-7873-1036
Buy that and it’ll last you a good few years, rather than only just being adequate right now. Even better, add a cheap GFX card with an HDMI output on it, something like the following link, and it will play HD video til your heart’s content…
http://www.ebuyer.com/264008-asus-hd-5450-silent-1gb-ddr2-dvi-vga-hdmi-pci-e-graphics-card-eah5450silentdi-1gd2
EDIT: Or just buy the PS3! But certainly don’t waste any money on a PC that’s several years old already, unless it is nearly free… Like I said, my 6 year old Dell was higher spec than the first one mentioned, I struggled to give it away, and it had 2Gig of RAM in it and a seperate GFX card!