There was a thread a while back about this, and in case folks don't know. C Board has a team. I recently joined it but we are slipping and we need YOU! *points in an uncle Sam manner* links:
EOC Ranking page for the team: http://folding.extremeoverclocking.c...php?s=&t=43476
Home Page of the project: http://folding.stanford.edu/
The team number for "The Cboarders": 43476
Make sure if you are on a multicore system, grab the SMB version, it is made for up to 4 cores.
This will make your computer create a bit more heat, but most computers are fine to handle this, it is primarily a concern on laptops, make sure you either have enough cooling near your laptop to run it, or only run it at 50% of the processor so you do not create as much heat.
Yes, task manager will say you are running at 100% CPU usage, that is because it is taking up every spare cycle it can get. But the work thread for the folding program is set at the lowest priority, so rarely will you see usage issues, I can game (processor intensive games like Supreme Commander) and not see any detrimental effects, granted folding@home runs extremely slow during that but it is ok.
Oh and this helps humanity! But really, making Cboard at least a top 500 (maybe even higher!) team is more imporant!
EDIT: Oh, I forgot to mention that anything less than 500Mhz(or whenever the SSE/3dNOW! stuff was implemented) is too slow for this, they wont complete the work units before the deadlines. At least 1Ghz is recommended.