Glad to see someone else joined the dark side!
Indeed it will fit your mobo, but I wouldnt reccomend it.
Youll get far better results from buying your own components and building your loop by yourself.
The Aquarius III has an 80mm form factor radiator and a matching 80mm fan. On average, (based on the daddy of water cooling radiators, Thermochill) an 80mm radiator will dissipate 100W of heat.
The Athlon 2700 kicks out 68 W of heat at its normal frequencies, and has reasonably high temperatures (my mates runs at 45 degrees idle) and as you can see, a 80mm form factor rad doesnt leave a lot of overhead for anything but adequate cooling.
The same level of cooling can be achieved by using a ThermalTake HS/F combo, albeit at a fraction of the price.
If you look at the radiator I'm going to be using (Thermochill HE 120.1) it dissipates 250W of heat. This is more than adequate to cool my overclockied 2500, and is good enough to cool anything over that upto at least 2.5 Ghz. Another benefit of using a bigger radiator and fan combo is the decrease in noise (120mm fans shift loads of air but dont have the bloody annoying whine to them that 80's do) which is always good.
So personally I would advise that unit.
I could spec you a good custom system for about the same price tho if you like ?