My fiancee's uncle bought a cheap (£35 reduced to £15) Samsung DVD combo drive from Play.com a few weeks ago, not realizing he can't use SATA. So I did a deal with him, and straight swapped my Sony DVD combo IDE drive for his SATA drive.

Not only do I now have more IDE bus slots for older HDD's, but I have a drive which is ~10% faster

Need to rip a CD into iTunes and burn a DVD to see if I can notice the difference, but so far so good