Installing XP MCE on RAID drive

I have just installed 2 new 250GB drives (RAID) in a new Sony PC that came
with XP home installed - performed system recovery so XP home installed on
the new drives.

I am trying to install XP Media Center Edition on the computer in a
different partition (i.e. muti boot).

The computer has an Intel 945 chipset and I have downloaded the RAID
controller from Intel and created a floppy.

I have pressed F6 to select install RAID controller for ICH5R

When get to the next step and select install Windows XP, there is only 1
drive showing with a 468 MB repeat megabyte partition. I don't understand why
it can only see 468 MB partition when 2 x 250GB drives exist on the system.
When I boot into XP Home, both drives are working correctly.

Does anyone know what to do to get this to work?