Optiplex 755 RAID 1 logical drive configuration ignored by FreeBSD 9.0-R installation

Fri May 18 20:10:31 UTC 2012

I created a RAID 1 drive in a Dell Optiplex 755, using the internal RAID 
controller and two 160GB drives, naming the logical drive "freebsd90". 
Within the system setup menu, the boot menu shows that "freebsd90" is the 
first (and only) bootable hard drive.

Yet when I try to install FreeBSD 9.0-R, FreeBSD ignores the hardware RAID 
and sees the two separate drives, instead of seeing a single logical 
drive.

Is there a way to get FreeBSD 9.0 to recognize the Optiplex 755 RAID 1 
drive?  If not, can I just install FreeBSD to one of the drives and expect 
the hardware RAID to mirror it properly?