For home systems, stay with the IDE unless you are planning on playing alot of games that require fast speeds. But you won't see a difference unless you are using a high end processor, alot of ram, and a high end video card to use that speed.
SATA is mainly for servers. The webserver I'm working on has 2x 80GB SATA on RAID. This is where it would come more in handy. Or you use it for a inhouse file server with several people accessing it.