Sata is the ONLY choice for mounting to one of the sleds in a MacPro. The computer comes with the sleds, all you need is a drive, no extra cables, connectors or anything else.
WD Raptors spin fast, transfer data fast and die fast (from heat). If you don't need the performance of a Raptor don't get one. You could exceed the throughput of a Raptor by plugging in a pair of 7200RPM drives (using 2 of the provided sleds) and setting them up as a soft raid. The Mac Disk Utility can do this for you, check the online doc files.
If you don't need RAID don't do it. Setting up a two disk RAID also doubles your chance of data loss due to hard drive failure.
If a standard 7200 RPM drive can't meet your throughput needs you could add another drive and manually split up where your data resides on two drives. Just having your OS on one drive and your data on a second drive will provide you with A LOT of throughput and none of the hassles of RAID.
I've used Western Digital, Maxtor and Seagate drives for years. Seagate is now the parent company of Maxtor. I've never had a problem with Maxtor. I've had a few Seagates fail. I've had a lot of problems and failures with WD but that was mostly on Windows PC's and I have not had any of those in the shop in over four years.
OWC in Chicago is a big Mac supplier. I've received good support from them and they have low prices. Here's a link: http://eshop.macsales.com/
Best of luck to you.