Guinea pigs are normally very gentle and sweet. They will [almost] never bite for no reason. If you are really thinking about getting him a guinea pig, you might want to check out these sites.

-http://www.cavyspirit.com/
-http://www.cavycages.com/ (it shows you how to make your own cage and has a message board, too)
-http://www.guinealynx.info/ (This one is probably my favorite, so much info! Taffy had so many health problems that I checked out that site a lot and their message board is great, too)