From what, I've read, the performance difference is insignificant.
If you were buying them new, it would make sense to get SATA because it's only a few dollars more expensive. It's definately easier to deal with SATA cables that IDE cables.
You won't be able to get much for the drives, so I wouldn't sell them unless you can't use the space or you want Raptors.
If you want to use SATA because your motherboard has SATA RAID or you have no room for IDE devices, get a couple PATA to SATA adapters.
If you're using Linux, IDE's easier to deal with, although the 2.6 kernels do support SATA.