It is my understanding that SATA is a lot faster for drive speeds and disc access.
You've listened to the advertising.
The fastest disk drive on the planet doesn't have sustained transfer speeds much over 70 MB/s. Parallel ATA tops out at nearly twice that. So the fact that SATA offers even more is deeply pointless.
The advantages are that most of the newest drives are coming out only in SATA versions, and they have features that don't appear on PATA drives. That's all. Back when SATA came out there were a lot of benchmarks of drives that only differed by interface and they were identical in performance.
Oh, and a final note -- if you get a SATA boot drive you will have to boot off floppy to install XP (or anything other than Linux), because XP won't have the SATA drivers on the CD. You can build your own CD to get around this, but I don't know what's involved in doing that.