Perc 2/Si in PE2400

I have a PE2400 (tag K8I7J) with a Perc 2/Si RAID with three 9gb drives in RAID 5. I am considering upgrading to Server 2003 next year but as 9gb drives are no longer available it's not feasible to just add more disc to extend the current RAID 5.

What I am thinking is, can I take out one 9gb drive (leaving 2) and then set the Perc 2/Si to RAID 1 and then having set up W2K3 etc on that disc configuration, install a couple of 36gb drives in a second RAID 1 pair?

I did do this on a PE2300 with a Perc 2/SC but am not sure whether the Perc 2/Si will handle two pairs of drives in RAID 1.