Sorry, even for that price (Google tells me that's about £270), you could of probabily put something together yourself for a bit better.
Problem is compared to AMD X2s and Core 2 Duo, the Pentium D is pretty much obselete. If you were to buy your own hard drive you would find it quite cheap these days to buy something quite cheap at 160 - 200 GB. If I were you I would defintly look at adding another 512 MB of ram, it will make a difference.
I googled the "RADEON X300 SE 128MB HyperMemory" and according to this:
http://www.hothardware.com/viewarticle.aspx?page=2&articleid=662It is actually outperformed by a NVIDIA GeForce 6200 TurboCache 128.
For the price you're talking about I would highly look at getting something like a GeForce 6600 or 6800 (you can get some pretty good versions of these, clock speed, memory type and features all matter, try and see if you can get a site with some feedback or check up a site that benchmarks them). If you don't play much games that were made in the last 2 years, I guess a 7300 would be perfect then.
