I agree with what the other poster said regarding just going to phase change...your budget is high enough that phase change is doable, since the system you listed is nowhere near a $2400 system.
$180 for the mobo
$180 for the CPU
$260 for the RAM (although the prices keep falling on RAM)
$380 for the 6800 (although if you wait a little while it'll be around $299)
$150 for the HD (wait for a sale)
$130 for the PSU
$80 for the DVD burner
$70 for the sound card
$50 for that laser mouse
$100 for those speakers (even less at some places, but monarch has them around $100)
$50 for the keyboard (probably an overestimate)
It comes out to $1600 in my estimate, which should leave PLENTY for phase change, even more slack would come if you made a couple of changes that would hardly affect performance, for one thing that OCZ ram could be substituted with any UTT chipped product, like the $62.99 a stick mushkin blue at outpost, and you could save a little more on the video card end by either waiting for the PCI-E prices to come into line with the AGP parts, or going X800XL.
Just by replacing the RAM with $100-$130 PC3200 UTT dimms, you'd save enough so that your whole system would be sub $1500 and leave $900 for cooling-which is way more than any water cooling setup costs (within reason obviously).
In case you don't know what I'm rambling about with the UTT:
2-2-2 @ 270Mhz...
Why pay some ridiculous price for OCZ when it's really the same stuff under the heatspreader anyways. If you read the specs on the OCZ it's pretty obvious that it's the same thing, since it's voltage requirements at 500Mhz look a lot like UTT voltage. Pretty much everyone is able to hit 250Mhz with very tight timings on the mushkin blue, although the 270Mhz at 2-2-2 is admittedly very exceptional =)