Advice for LOAD BALANCING Board that can handle 100mbps

Hi,

I am newbie in these parts.

I need a 4 WAN Load Balancer that can handle 4 X 25 mbps WANS.

I know that the 680 mhz boards can handle a lot of throughput but according to this explanation from pfsense it should need more power to do that well.
take a look
http://www.pfsense.org/index.php?option=com_content&task=view&id=52&Itemid=47

The Mikrotik RB1000U has 1333 and 512 ram, but it is discontinued i believe. Do you know if it is older tech chips and if the 680mhz match or out perform it?

Any help on a round robin type load balancer and the commands to make routerOS only do DHCP or MAC based static ips with a 4 wan load balancer is all I need.

Thank you very much!

Here is the detailed information about every RouterBOARD throughput with different kind of traffic/configuration,
http://routerboard.com/pdf/routerboard_performance_tests.pdf