NIC LOAD BALANCING

I have one cisco 6509, connected to 2 cisco 4000’s
my servers are located behind one or the other 4000 and i want to add the second NIC. i want one NIC per 4000 for redundancy and i would also like to accomlpish load balancing if capable. I have read up on NIC teaming and WLBS. Our intel cards support AFT and ALB. The range for these 2 4000’s are using the same subnet. i have a WINS and DHCP server on each 4000. Would i have to upgrade my cisco IOS or CAT-OS to support these features & or willthese options be available by default