I was in the same boat as you a few months back before i decided to make a water loop for my next rig. Well in the end i couldn't afford it but know i know a whole lot more than i did incase i want to build one in the future, which i so
Obviously you understand you'll need two blocks for the gtx 480's. Full blocks are good but not necessary, i have been told a good gpu block paired with some decent zalman ram sinks is the best bet.
The two best CPU blocks currently are the EK surpreme and the swiftech XT. The Xt being slightly better in most cases but does limit flow slightly more.
The pump you want to get is the laing ddc pump. There are a number of revisions and makes as they are kinda like graphics cards. The most common is the swiftech mcp-355 which is currently made in the second revision of the pump (there are three; the first was 3 then 3.2 and now 3.25) each one offers slightly more head pressure then its predecessor. Dangerden and koolance also make the newest revision. Since your in Australia too, www.gammods.com.au
is the best place to get most parts, pc case gear are good for blocks i've found. Gam stocks the actual laing ddc3.25 itself so its great to get from there. You might be thinking what about the laing d5? well after extensive research it seems it only provides a better flow but does not carry as much head pressure so the ddc paired with a aftermarket top is the best choice.
The Top allows you to connect those "barbs" to the pump through universal threads, usually g1/4" thread. the best tops for the ddc are the Ek X-top rev.2 and the XPSC top. A top is a must for most because the replace the front casing of the pump and allow you to connect through fittings you choose, instead of using the default plastic which can break if your not careful, they also increase head pressure some more.
The barbs your having trouble with are just the standard fittings most people use because they are economical. They screw into the radiator/pump/blocks etc through the universal threads i talking about so you can clamp a tube onto them. You can also use compression fittings which look the nicest for a final product, this way you don't need cable ties or worm clamps things which make the loop look less pleasing to the eye.
If your after a triple 120mm rad, the thermochill pa120.3 (15mm version- new) is THE king. It's a great rad for a range of fan rpms and cfm's. The others that are very close are the Black ice GTX series which is better for higher RPM fans and the FeserOne extreme series. But both are hard to get here and usually more expensive anyway. The swiftech regular series (not quiet or slim) are also very good for a budget cooling loop.
I think that covers most parts, the res doesn't really matter, but i had my eye on the EK 150ml res as i dont fancy bay reservoirs. Your best bet is to post a setup on extremesystems under the water section, to double check with a finished loop. If you want great temps i think you'd be better off getting a seperate loop for the gpus alone and one deedicated to the cpu/nb/mofsets.
Just ask for any more questions i should be able to help some more.
EDIT: should add that the best coolant is distilled water with a couple drops of a good biocide which you can find the name of on the internet. The best tubing by far is Tygon, it is generally good to try keep all your fittings and 1/2" inner diameter and use 7/16" tygon tubing for a really good snug fit. But 1/2" tubing as your supposed to use works well too. The tygon tubing was used for medical purposes and does not kink easily, its worth the extra cash because you wont need any coils to stop kinking.