How slow should software raid be compared to Hardware raid controller on average?

I am creating a replication data server and I can't beleive how slow it is to copy files to the the drives. I also have a virtual machine on a raid 10 (4drives) 7200 rpm Sata and it runs super slow.

I have jumbo frames enabled on the ethernet cards with bonding enabled (2 Intel 1000 nics).

Is there something i should check for or is it normal that it is that slow.

Server Specs
dual Opterons dual core each 2GHz
12 GB Ecc Ram 400DDR
Onboard Gigabit Ethernet
PCIx Intel Pro 1000 MT dual Nic (bonding)
4 Seagate 1TB Drives Raid 10
4 WD Caviar 80GB Raid 10

I am running software raid because I am out of expansion slots and the board does not have PCIx slots only pci. The Intel Nic can be used on PCI or PCIx.