We use Tide HE, Purex HE, Wisk HE. Liquid works better for us than the powder or pellet. Wal-Mart, K-mart, Acme, A&P sell it as does Sears.
My wife's friend has a front loader and the friend uses 1/2 the normal amount of regular detergent. You can do that too.
Tip: Let the gasket on your washer dry out between loads or it will get real moldy. You can search other forums for moldy gaskets on front load machines.