Blocks
Basically, just read reviews and google things, there isnt much tech specs too them other than what fitting size they use, but the pump i showed you has several different fitting, but 3/8" is common and you want to keep it as simple as possible, adding fittings, will add a lot of money.
http://www.frozencpu.com/products/2...pper_Water_Block_Intel_775.html?tl=g30c85s140
if your going to liquid cool your graphics get this
http://www.frozencpu.com/products/6...ling_Block_ZM-GWB_8800_GTS.html?tl=g30c87s585
basically the cheapest 8800 block, but they all do the fairly same job, only thing "cheap" about it is that its not copper
EDIT
there IS a difference between gpu blocks, and vga blocks, gpu blocks ONLY cool the gpu, you would have to heatsinks for the ram and stuff, but with that vga block it covers everything you need
Reservoir
You dont need one to be able to have a kit, but they come in handy, they give you peace of mind knowing that if there is a tiny leak, that you will be able to notice by the level of your reservoir dropping, and normally leaks cause fatal damage because air gets into the system, they also make it much easier to fill the system with the coolant, and it only takes up a 5.25" bay so space isnt a factor, here is the one im looking at
http://www.frozencpu.com/products/2...aBay_M3_525_Reservoir_CL-W0031.html?tl=g30c97
Radiator
Pretty easy here, there is basicaly only one thing to choose from, and thats the size, i would reccomend this
http://www.frozencpu.com/products/2..._Black_w_Customizable_Fittings.html?tl=g30c95
it has 1 120mm fan, its from danger den (the best for wc parts), and its compatible with the 3/8" setup ive been following
Tubing
Again pretty straight foward, get the right size and enough length.
http://www.frozencpu.com/products/4...Wall_PVC_Tubing_-_UV_Green.html?tl=g30c99s171
UV Green and its 2$ a foot so not bad at all, in my cart i put in 10 feet, which is more than enough but since this is your first time then you might need it if you make a mistake.
Coolant
I would go with a brand you know is good, thats why i choose this stuff, and its a big tub, so if there is leaks the first time around you can replace it
http://www.frozencpu.com/products/6...gh_Performance_Coolant_-_1000cc_Cl-W0148.html
Fittings
Well, i added 8 of these clamps just in case you need them, there only 1$, so it never hurts to have a proper clamp lying around
http://www.frozencpu.com/products/2263/ex-tub-11/38_ID_Reusable_Clamp.html
You might need some other fittings if you run into problems, but you can order them later if you need them, but you dont know which ones you might need, i would get at least 2 elobows though, youll probably need them for your pump because it will be in the corner of your case, but i would just wait, find out what exactly you need, then go from there.
Overal thats 315$, with the VGA block, though most people only cool there cpu in which case, it would be 235$, both ways its pretty expensive, and these arent tip top parts, but it certainly beats a regular kit. Dont the the VGA block if your going to upgrade soon though, it probably wont fit the new cards, but the LGA775 looks like its going to last quite a while, so it might be worthwhile getting a better block if your future rigs want to be Liquid Cooled.