SATA is the emerging technology although there aren't all that many devices yet available and, I understand, there is a price hike. Speed and capacity are the main benefits, but it depends on what you want to do. Some useful links:
I have already got 2x120Gb SATA's,I have just spent the best part of 48Hrs reinstalling XP onto them.They are faster than IDE hdd's,but only marginally and also only faster in windows.Try doing anything in DOS and your in for a week long wait,it took XP 2 hours to format 22% of a 10Gb partition.DriveImage(Caldera DOS) takes upto 4 hours to reinstall a 1.5Gb image,and often fails in the last few percent.There are supposed to be new revisions of SATA technology,so if your adamant you want SATA,I would wait a while yet.Also,the Si3112 drivers available aren't M$ certified(yet)Mine keep vanishing during reboots,and XP fails to load.
My 2 x 200GB SATA HDDs have been no trouble at all once they were successfully installed, and all that needs is the proper drivers for the motherboard, as they are not yet in XP, or at least that was my experience. Mine are not in a Raid configuration, although they are affected, it seems, by the Raid controller on the m/board. You just have to ignore that they appear to be called SCSI drives which is what Windows insists on calling them.
I have a couple of Maxtor 80Gb SATA drives installed. No noticable difference in speed, no problem cloning with Ghost(takes 15 minutes as it did with IDE drives). However what made me buy them was the fact that I can run 2 hard drives, and still connect up to 4 IDE devices without having to install a seperate IDE controller card. I now run the 2 SATAs, 1 DVD ROM, 1 CD-RW, and 1 250Mb Zip drive.