I remember when people were hitting 3k ppd. It was like they were from the mother-ship. Like TB said, graphic cards are the only way to rack up some serious points. Even something as mundane as a 9600GSO, when overclocked, can easily produce 4k ppd. For the bigger cards, you’ll need to upgrade the computer’s power supply, but that’s a real easy change.
A while back, SazanEyes sent a link to me describing his rig. I’ll see if I can find it. It’s a freakin’ beast!!!!
Here’s the link to the machine that generates most of my points:
http://www.sazan.net/dpark/gauri.shtml
I don’t have any pictures of my other box online yet, but I do have various computer pictures here:
http://s722.photobucket.com/albums/ww222/sazaneyes/
Those machines are running GPUGRID and various other distributed computing projects.