Sounds like some people are just going with really expensive stuff, like the FX-60 is not needed when you can easily overclock an opty (especially with that water cooling) it equal or maybe better then a FX-60.
also the X1900XTX is not needed now i owuld just save my money can go with a 6800GS which will last you with great setting until the DX10 cards come out later this year.
well here's what i would do.
DFI Lanparty Ultra-D
Opteron 165 or 170 you can chose
6800GS or maybe a 7800GT which will both be good till DX10
WD 150gb raptor im pretty sure you can raid it with your 74gb
thermaltake xaser is a good case not my style but not my choice
antec truepower 550w like you posted
sound if you want speakers go with the Z-5300's if i remember right
if you like headphones go with the Audio-Technica ATH-A900's
if you want to overclock go with some mushkin extreme performance DDR500 http://www.newegg.com/Product/Produc...82E16820146397
gave you a link cause there are 2 different ones and those are the best
Air cooling is fine you can get an opty 165 around 2.8-2.9ghz with a zalman CNPS9500, it's been done ask 003 or just check his sig.
im pretty sure that covers everything. could you post the specs of your monitor cause if the response time sucks then you can get this beast
im pretty sure this is the best one.
just save whats leftover for the DX10 card later this year.