I'm currently looking into getting a 74GB sata WD raptor drive and 2 250 GB sata drives and getting a new computer.   The XPS has 2 sata connectors that can be used in raid configuration.  What I want is a system that has the 74GB drive as the boot, and then 2 250 drives mirrored off each other and used for all my data.  Since most computer only have 2 connectors for sata I'm looking at getting an explansion card for around $50.  But I haven't been able to find any with raid support on them.  All they provide is just a normal config.  I'm either looking at putting the 2 250s on the motherboard and booting the 74 off the expansion card, if I can,  or I would rather put the 74 on the motherboard since the motherboard sata connectors are on a faster bus than the PCI expansion card would be.  Since 74 drive will hold all temp, programs, windows, etc.  I want it to run fast.  The 250s are for data so they aren't as much of a concern.  Just need to know what will work.