In my situation, I noticed the distributed.net client running very slow. I ran wintop.exe, a windows Powertoy, which is freely available from Microsoft and also downloadable as a standalone utility from add-ons page, to determine what programs were using the processor. Surprisingly, the client was only getting 2-3% of the processor time and the keyboard program was using 95-98% of the idle time of the computer. Once multimedia buttons were disabled in windows control panel, the client increased it's speed dramatically.

For HP computers, go to control panel, select Keyboard and then deselect "Enable multimedia buttons and onscreen display" so Windows will not use processor time to continually check multimedia keys for presses.