I run a 9600GSO (nVidia GPU) and a VMWare'd Ubuntu Linux SMP client on my Opteron 165 (i.e. X2 with bigger cache), overclocked from 1800 to 2556 MHz, on XP Pro. The way I got them to produce best was to run a little utility every once in a while to make sure the VMWare executable is at Below Normal priority, and to fix the messed up GPU client code which only gives the GPU core one core of the CPU. And I also increase the GPU core's priority to Normal, too.
Rather than do any real work, as usual a search engine allowed me to download the utility which can change any program's priority and its processor affinity. It's called process.exe, and I got it from
here. Since the GPU client kills and respawns the GPU core every time a new WU is downloaded, and that happens every 2 hours and some, it has to fix the settings fairly often. Since I'm not always around or awake when it's doing that, I needed to run a few scheduled tasks to fix things. I run 3 scheduled tasks: one to fix the GPU core's priority every 3 minutes (it takes practically no CPU time to run these things), one to fix its affinity every 5 minutes, and one to lower the SMP client's VM's priority every 30 minutes. That way, the GPU client, which can supposedly deliver over 5000 PPD, will usually never wait more than a minute or 2 before it is getting the optimal amount of CPU time it needs to run at full speed. The SMP task only runs every half hour because it generally isn't going to re-launch unless I restart the computer (which is very rare) or suspend the Virtual Machine, which only happens while I'm working on it and need the CPU. The reason I have to do that is because the GPU client can really screw up screen refreshes, making them take too long to be useful for work.
Running them together, I get over 5700, and usually (FahMon claims) over 5800 PPD with the slowest SMP clients, and above 6500 with the faster ones. I run it that way after I quit using the machine for work, but doing anything that redraws the screen or uses much CPU time really eats up the speed.