You can’t have too fast computer or too much DSP. The easiest way to get both is to upgrade your Pro Tools HD rig with Mac Pro and the new Magma 64-bit PCI chassis. You can keep your PCIx HD cards and even add few for more mixing power. We just did it in our showroom and the raw speed of Pro Tools HD|5 Accel on a Mac Pro with 64-bit Magma PE6R4 Chassis almost blew our socks off. Luckily we were wearing shoes so no damage was done.
But seriously, to feel the speed, grab a Pro Tools session and drop by to see how you can save time and money by getting your gear up to date. The Mac Pro boots in 20sec and Pro Tools is up appr. 3 faster than on G5. To get us to match the speed, we had to upgrade our coffee machine as well.