Flinx

If your going to stick your case in a cubby hole and leave it there then liquid cooling is not for you IMHO. Besides unless your Overclocking you really don't need it.

Your power supply is important! I can't really stress that enough, buy a good one.
PC Power and Cooling, OCZ, Corsair and Antec would be my choices in that order.
500 watts is the minimum I would consider, 750 is better and the price differances between them I'd go for a 750watt.
PC Power & Cooling Silencer 750-Watt is a good choice I'd say.

Next up is what CPU, well you already stated a Intel i7 920, the 975 is crazy expensive and again not worth it unless your into overclocking.

This brings us to your video card(s). ATI or NVidia. My personal choice is ATI, I like their drivers and their customer service. The very few times I've had problems with a ATI card they have bent over backwards to help me up to and including RMA'ing one card that was out of warranty for just under 2 months, now thats customer satisfaction in my book.
If I had the money I'd get 2 XFX Radeon HD 4890 XT, but remember this is a personal preference others are going to say CrossFire/SLI is a waste, not when your gaming it isn't IF the game your playing can take advantage of it.

Now you need a motherboard, just about any Intel X58 chipset mobo will fit the bill.
Asus, MSI and Gigabyte make good ones. I like the Asus Rampage series myself but I'm thinking cost is a bit high and a bit too much bling so I'd recommend the MSI Eclipse.

Now onto Memory. OH wait what Operating system? Windows 32 bit or 64 bit? XP Vista and Win7 all have 32 an 64bit versions. If your staying in 32bit land 4gig of RAM is your max because thats the MOST you can address and you don't get all of it even so. So 64 bit? Well it has other problems as well, drivers seems to be the biggest problem I run into myself. Since you've stated that this is gaming system I'd say either XP Pro or Win7 (go Win 7), here is where you and your builder need to sit down an talk 32 bit or 64 is the big issue, IF you can get all the drivers and make them play nicely with each other 64bit and 6gig (in a matched set, 3 sticks). OCZ, Kingston and Crucial are my choices in that order. OCZ Platinum Tri Channel.

The case you selected before is a good choice.

Your stated your desk is a problem
Any chances of cutting a hole at the back of the desk and putting a small fan there to keep air moving? Even against the wall there is usually a small enough space to allow air movement with a little help. Just a thought and this method has worked before for me.