If you don't like it...
Now, I'm expecting to get a lot of grief for the choice of components going into this 'gaming' rig, but hear me out. Each component is well thought out and is ideally suited to building a rig in a flight case.
The motherboard is a GIGABYTE mATX GA-G33M-DS2R and while this means I cannot SLI it up, it also means that it fits in the case! A newer chipset like the G33 is perfect; supplying onboard sound and LAN and keeping it budget at the same time. We're not going to break the bank on something that will be shoe horned into a cheap-ass case from a DIY store.
The graphics is again GIGABYTE, but a new series 9600 GT NVIDIA card and these have been getting awesome reviews. I think it's perfect bang-for-buck for a system like this and it runs everything out there at time of writing, including Crysis (well, maybe not on full, but it's playable on mid-range settings). I also like the Zalman fan unit they mount as stock on this card; it helps to keep the temperatures down and moves a lot of air around inside the case.
The RAM was a tough choice, but in the end we went for Kingston HyperX DDR2 PC2-8500 modules because these babies can clock right up to 1066MHz with no problems. It's important to balance the system right in order to get a decent performance; there is no point skimping on any one of the four essentials which are the motherboard, graphics, RAM and CPU.
Focusing on the CPU; I might get some flak for this, but I stand by it. I picked up the lower spec new Core 2 Duo 45nm Wolfdale. Why? - Well, it's cheap, it's available and it overclocks like a monster! The 3GHz model isn't that much more expensive, I realise that. But it just wasn't necessary. If you balance the system as a whole then it shouldn't have a problem with a slightly lower spec CPU. Not to mention, the thermal output of the lower spec is better, so it won't cook the inside of the case.
The big question was how to power this rig and we wanted a PSU that was adequate for what we had, but at the same time had a nice big fan that was seriously hush hush.
Thermaltake popped us an offering of their new TR2 QFan Series at 400 watts. This thing is perfect. There's a HUGE fan on top, 400 watts of clean juice and an 80+ power efficiency rating.