What's your spec at the moment Gaz? Would also be useful to know the make and model of your pc if it's branded orthe motherboard make and model as well if you have a non-branded pc.
Are you using Vista or XP (and which version)?
What sort of things do you do on the pc and what things do you want to speed up?
If you answer those questions I'm sure myself and a few others can help you out. But if you know what you need already I've used these sites in the past:
www.ebuyer.comwww.dabs.comwww.overclockers.co.uk