[CentOS] Centos 5.6 3ware raid 5

Hi, I've seen comments about the poor performance of these cards with raid 5 configs. I have an old card with 3 x 500G IDE drives connected in raid 5 and I'm getting around 10mb/s write performance. :-(

I'm seeing high iowait figures at times and associated very high cpu load average figures, probably because, under load, everything is stacked up waiting for the disks to actually do something.

A non-raid sata disk in the same machine manages 70mb/s

Does anyone know what the performance is like if I used the 3ware just as an IDE controller? I could then switch to software raid5?

Thanks

Ken