Is this spec any good?

I am looking to buy a new PC so that I can run newer games at descent quality, I don't have alot of money to spend on a new computer so I looked at a website called www.pcspecialist.co.uk were it lets you choose custom parts for your pc, they build it for you and send it out. I have about £500-£600 to spend and I was wondering if this spec is any any good for running todays games and if it will last me a good 5 years or so;

Intel Pentium 4 (3.2 Ghz)

1024mb RAM memory

256mb Geforce 7900GS

all other parts like the sound card and stuff is standard and I chose a 500W cooling fan, is this a descent spec? it will cost me £549, also another question, which is the better processor for running games? Intel Pentium 4 (3.2 Ghz) or Intel Pentium D 820 (2x 2.8 Ghz)?

Ok I have had a look at the Athlon x2 processors and I came up with this new spec for the same price, is it better than the Intel spec?

AMD Athlon 64 x2 4000 (2.1 Ghz)

1024mb RAM memory

256mb Geforce 7900GS

give me a few examples on how this will run certain games, e.g. F.E.A.R, Battlefield 2142 or World of Warcraft. By the way my current pc spec is;

Intel Celeron D (2.88 Ghz)

512mb RAM memory

128mb Nvidia Geforce FX 5200

as you can probably tell from the spec I really do need a new PC to play newer games, will I notice muc difference between my current PC and the AMD or Pentium one I am thinking of getting?