Upgrading computers is always great fun, my experiences usually go like this:
I like that new powerful CPU, ah, but I'll need a new motherboard to support it, oh and I'll need to replace the RAM because the RAM I've got isn't comparable with the new board, hang on I'll need a new graphics card because the new motherboard has a different slot and the old card won't fit....
And so it goes on and the price starts mounting up!