for cpu i recommend the swiftech apogee gt (not gtx, its no better just a rip off)
http://www.newegg.com/Product/Product.aspx?Item=N82E16835108093
i doubt you could WC the mobo since it would require taking off ALL the heat sinks. the stock cooling is fine i think, but if i were to go with a 780i i would get this MSI which has even better cooling
http://www.newegg.com/Product/Product.aspx?Item=N82E16813130158
if u are going to tak off all th stock cooling then ether swiftech MCW30 or go to pcwatercoolingshop.com for a more buget chipset cooler (i own a OVV-M2 Chipset Block and i works great on my OCed p35)
as for a gtx 280 if money is not an issue (which shouldnt be since your buying the cards lol)
http://www.ncix.com/products/index.php?sku=31680&vpn=3830046993489&manufacture=EK%20Water%20Blocks
or
http://www.newegg.com/Product/Product.aspx?Item=N82E16835108096 +
http://www.newegg.com/Product/Product.aspx?Item=N82E16835108095
Pump,
http://www.newegg.com/Product/Product.aspx?Item=N82E16835108082
rad,
http://www.newegg.com/Product/Product.aspx?Item=N82E16835108086 should be okay but if your overclocking get
http://www.newegg.com/Product/Product.aspx?Item=N82E16835108098 or two of the dual one
tubing get swifttech 7/16ID
additive get swiftech hydrx
OR!!!!!
get the everything except the extra rad, video and MB block as a set
http://www.newegg.com/Product/Product.aspx?Item=N82E16835108076
that seems like a killer sytem there
personally i wouldnt get such an expensive case, if its the big fans in that case that ur buying it for then forget about it if you have WC you dont need that many fans, i would get an antec 900 if i wanted that style of case, but right now in sporting a XION2 case, its not super quiet with the stock stuff but ive modded it alot, mainly i like it for the looks
also i wouldnt waste my money on a gtx 280
i just bought a radeon 4850, if i had a losser budget i would have got 2 4870s, dont get me wrong i love nvidia but the performance for the 4800 series is insance comparded to price and they use less power, 2 4870s will perform as good if not better than 2 gtx 280s, + the advantage of going ATI (never used to be any lol) is that you can use a intel chipset such as X48 which are faster than nvidia