Cheers for the advice guys! I tend to only buy one game then play through it, then buy another. I'm doing COD4 again at the moment, then I'll do CODMW2 once I've reinstalled the OS.
I'm set on getting shot of XP now. I only use it for San Andreas which I'm actually pretty bored with now, I just decided I wanted to have a go at it again and it's not as good as I remember.
Metacritic looks perfect for me, as I'm not really bothered how old games are, I just want to play the best ones.