MSA1000 setup and performance

Hi

I have a HP Proliant DL580G2 with 3*2.8GH XeonMP chips, 4GB RAM and 2*
HP 2Gbit/s Fiber HBAs connecting to two MSA1000 SAN Switch 2/8's
mounted in the rear of a MSA1000 (v4.24 firmware). Two external
shelves are fitted with 20*146GB 10Krpm hotplug disks spread evenly
between the shelves in a single RAID 0+1 config.

Win2000 Advanced with SP4 etc on the host.

With sisoft sandra I'm only getting 28MB/s when writing to the single
1.4TB dynamic partition yet 75MB/s read.

I haven't done anything with the SAN Switches other than out the box
and plugged in.

Any tips on how to get some grunt out of this, I need to write and
read 500MBish files quick as poss?

Ta