I have been running SETI for about 4 years -- I started just 4 days after the project started.
So, I may not be the person to convince you, but the Folding@Home program (I always use the plain text based client) is a lot easier to live with than SETI. F@H only works when your machine is otherwise idle, whereas SETI (the text based client anyway) always
runs, so you see the hit when you are trying to do something more strenuous with your computer.
As for the technical purposes of F@H, you should check their web page.
Our SPRC Folds! team page is here:
When you install the client, you'll need to enter the team number -- 31574 -- so the team gets credit for the work your computer does. Athlons are excellent folders, BTW! Your 1700+ will certainly add it worth. The only frustration (especially when you start out) is the servers are sometimes slow to "react" and the credit for your work is sometimes slow to show up, but it will...