ya you can
no problems.
Attach Raptor to regular SATA port on Motherboard. attach your 2 250 hds to 2 raid Ports on your motherboard. turn pc on. Go into bios and enable raid on the 2 ports that has the 250 hds. Enter raid setup utility, create a Raid 1 array. Start windows setup. press f6 to get (specify raid & SCSI controller driver). insert floppy with RAID drivers. Upload drivers. Enter windows HD Selection screen. Select Raptor drive and hit create parition. Create a parition which will be defaulted as C: then select the 250gb mirror array and hit create partition. Array should now be D:. install windows on C: and proceed like any other windows installation. After windows finishes installing. enter my computer and double click on D:, it will prompt you to format, format the array and you're good to go.
good luck. If you need any sort of help or have any other questions please ask.
This quick guide only applies to WIN XP and 2k and 2k3. Win 95, 98 and ME unknown.