1) Do a complete backup to an external drive just in case.
2) If these are not your system drives, you can
a) If your drive controller is set to the default IDE mode, tweak Win7 to work with AHCI / RAID mode chipset (search this forum), and reboot.
b) Build the RAID0 set in the BIOS. No drivers needed, to the best of my knowledge. WARNING: this will wipe everythng on your drives.
3) If you intend to move your system drive to the RAID0, that's another issue. You will very likely have to re-install the OS from a full Win7 disk, not the Dell recovery disk. The RAID drivers can be found in the Intel Matrix Storage drivers (assuming that this is an Intel-based system). But moving the system drive from non-RAID to RAID is beyond me.
So, the key question: Are you moving your system drive, creating a volume on empty drives, or creating a volume on drives that already have data?
Also, check out this post: http://www.tomshardware.com/forum/196922-32-switching-storage-controllers-reinstalling-windows
. A direct quote: "For instance, you may want to upgrade from a single-disk installation of Windows to a RAID installation,..." so it may be what you are looking for.