PC upgrade specs question.

[Fubar]

I'm thinking of shelling out on a new PC as my current one is a little long in the tooth now. I've been looking at pre-built systems like this...

http://www.pcworld.co.uk/martprd/store/p...tegory_oid=

....but i've started to realize how out of touch i've become with the latest gear, i thought dual core was the dogs boll's but now i see there's a quad core.

My current games PC is a P4 3gig with 1.5 Gig of memory and an nvidea 6600 256mb GC, what i'm after is a new system that's a few steps up the ladder and will last me for a while but not cost the earth to buy.

Any advice would be great.