Antec 902 Nine Hundred Two Ultimate Gaming Case - Black (No PSU)
Good cooling, don't want to fry components as we have no money to replace them.
Antec Signature Premium 650W Power Supply
Reliable PSU with enough wattage. Would like to spend a few more quid to get a modular one.
BFG GeForce 9800 GT EcoIntelligence 512MB GDDR3 PCI-E
Not as high spec as the other suggestions, but I have one of these in my main box and I play all the latest games at 1920x1200.
BFG offer a 10 year warranty, I have first hand experience with their RMA process, they replace dead cards in good time. I got a free upgrade with my RMA.
Asus P5QL Pro Intel P43 (Socket 775) PCI-Express DDR2 Motherboard
I don't know anything about this board, but I wanted to go Intel over AMD, and price didn't allow much.
Intel Pentium Dual-Core E5300 "LGA775 Core 2" 2.60GHz (800FSB) - Retail
I'm actually running a E6300 (2x 1.8) in my main box, it's never caused me any problems. I think ppl are spending more than they need on CPUs.
Western Digital Caviar Black 500GB SATA-II 32MB Cache - OEM
Cheap drive, decent capacity, 32mb cache.
OCZ Platinum Revision 2 XTC 2GB (2x1GB) PC2-6400C4 Dual Channel
Easy way to save some money, this ram will do nicely. Get 4GB if you plan on running a 64-bit OS. Can always do that later.
LG GH22NS40 22x DVD±RW SATA Dual Layer ReWriter (Black) - OEM
You'll use it once in a blue moon, but you need it to install your OS..
Arctic Cooling Freezer 7 Pro CPU Cooler (Socket LGA775)
I got a 15'C improvement using this over the stock cooler, wouldn't build a system without a custom cooler now.