I paid 350 for mine with a quad core amd, and this was when ram was double the price it is now. The i3 550 does look like a pretty good chip though, might even be better a quad core amd where it counts. I think if I was spending that sort of money the first thing I'd get is a fractal design define r3, but that's just personal taste. I'd get a better power supply too, something like a modular bequiet.
eta: oh, I would definitely not get the Arctic Cooling Freezer. I have a similar one and they simply do not shift enough air.
Built a pretty good machine a few weeks back for £220, Athlon dual core, Asus main board, 4GB of ram. a nice cooler master case and power supply and it is pretty fast, the Hard drive is only a 250GB mind you, but that can be expanded. It was done on a budget, but it is still a good machine.
Stuck a Venom on a mates overclocked I7, and i got a nano Venum on mine, does the job.
I forgot I also got a 23inch full HD Hanns G monitor as well, so that was £125. bluray writer about £80. so i suppose it cost me about £600 for the main computer bits, but not the power supply as i had that already.
Never really got into the modular PSU, put one in a my mates machine, the same mate that got the I7 and it did not make a lot of difference, I tied up the cables I have not used in my machine. Then the case is a good case, a Cooler master Haf, all the cables are stored behind the motherboard plate.
I am happy with my machine, it should last now for a few years, you could go on and on, the next thing now is PCI-E 3.0., not going to amke much difference to me. at least my board got Sata 3 on, which is a bit more important to me.
The only thing I may get at some point is a SSD unit and a larger mechanical hard drive.
Desktop machine now powered by windows 7 pro 64bit , laptop by ubuntu
On ADSL24 using C&W network.