SATA all the way. I didnt realize how much better it was until I transfered 1500 songs from SATA drive to my main SATA drive in 2 minutes. It took 20 minutes with my old IDE drives.
And its good if you are a gamer. Loading speeds are increased. Very noticeable if your coming from IDE.
Custom) Core2Quad 2.4GHz, 2GB DDR2800 RAM, Dual 256MB GeForce 8600 in SLI, 320GB SATA HDD