Yes you can. I run a 80gb on ide0 for storage & 2 x 60gb in RAID 0 for my system drive. If you are planning to run XP/2K you might need to unplug the ide0 device to properly install in the raid though.

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MSI 875P NEO-LSR Mainboard - Intel P4C 3.0Ghz (800Mhz FSB) - 2 x OCZ PC4000 512MB DIMMs - 4 x WD800JB 80GB/8MB Cache (RAID 0+1) - SB Audigy Platinum eX - ATi Radeon 9800 Pro AIW - Sony Trinitron 19" - Windows Server 2003 Enterprise