With a ABIT KT7a-RAID mobo, 1 45GB 75GXP, and buy.com's $137 price for another 45GB 75GXP, I
had to give in

If you got a RAID board, just buy another drive. If its not the performance that concerns you, just think of it as more space.
RAID 1 is is a waste of money if you ask me. here are my three reasons why:
1) If your data is not absolutely critical (by critical I mean losing data would cost you thousands of dollars, ie web servers), then regular CDRW backups are enough
2) The price tag of another hard drive without any added space/performance
3) Degraded performance
It my make sense for some, but for most of us, no go.