Hi,
I know you want hardware raid, but SME is geared towards Software raid. It assumes that as a minimum you have two drives and it automatically generate a RAID1 array. 4, 5 and 6 drives give you RAID5 (I think).
I have seen people telling in the forums about getting problems try to do hardware raid - the software raid interferes and you need to sort it out (somehow - beyond me, but others will be able to tell you; or it is already on the forum somewhere - do a search on the forums for hardware raid)
My advice would be to stick with the software raid - a nice fast motherboard/cpu/memory combo with big hard disks would do you very nicely.
Cheers
Ian