I think you made a mistake in Tricks and Traps, "Comparing SATA RAID and SCSI RAID," April 2004, InstantDoc ID 41803. In that Q&A, you said that "large" Serial ATA (SATA) RAID drives are available "only in 7200rpm models." However, I've seen 10,000rpm SATA drives from Western Digital. The drives come in two sizes: 36.7GB, which you can purchase for about $110 (OEM), and 74GB, which costs about $215 (OEM). Were you aware of these options?
Yes, I'm aware of the drives you mention, but by "large" I meant drives bigger than 100GB. A Western Digital 250GB 7200rpm drive costs about $200; if your main concern is storage, rather than performance, the 10,000rpm drives are expensive by comparison. (For performance, I'd still choose SCSI.)
If you're set on SATA, be aware that most SATA motherboards support RAID 0, 1, or 10, which certainly isn't optimal, so you might consider also buying a SATA RAID card, such as the Promise Technology FastTrak S150 SX4-M (which costs about $150) or the more full-featured LSI Logic MegaRAID SATA 150-4 (for about $250).