Yea get the fastest RPM you can afford make sure it has at least an 8MB buffer as well. To answer your other question ATA stands for "AT-Attachement" the standard goes WAY WAY back. For those of vetrans of the early PC years it was the godsend taht replaced MFM/RLL hard drive technology.
No question about it get the 60GB 7200RPM the faster speed with the 8MB cache is very nice to have. Loads games faster and spends less time finding files on CDs so its doesnt have to uses the Hard Drive as long or as much. Even thought your giving up 20GB of space you can always make that up with getting a 2nd hard drive either internal using the smart bay or an external hard drive connected though USB.
Serial ATA hard drives have a smaller cable running to the motherboard than IDE drives. Look at the black part of a mechanical pencil; it is that width (1.25 inches wide max). It also transfers data to the motherboard faster than its IDE counterparts.