List of computable drives from NewEgg.com found here: http://www.newegg.com/product/ProductList.aspx?Order=PRICE&Page=1&Category=15&Nty=1&N=2010150380+1035907918&Submit=ENE&SubCategory=380
You should PROBABLY start checking out Sony's site on standard questions like these, since this is not a "hack" or unwanted modification.
2.5 " Laptop hard drives are what will fit into the ps3. If you are looking to use a 3.5" desktop hard drive I believe executer has made an adapter for the ps3.