I've used a couple things over the past several years to impliment this, I didn't need more than 20 ports. First, I daisy chained a couple of these
http://www.newegg.com/Product/Produc...82E16833122111
But, then moved up to one of these recently, when it was on sale for 119$. It happens every couple months or so.
http://www.newegg.com/Product/Produc...82E16833122146
All have worked excellent, I am getting a true 600-670mbs throughput around the ranch house.
Originally, I had a cisco that was about four years old, and I had a couple subnets setup so the slingboxs could carry their traffic uninhibited to their dedicate cable out. But that was overkill.
I find ebay has a LOT of nice units for great prices