What's your budget?
If the Kenwoods speakers you have were part of a HTIB set then just about any receiver will work. You can get a good qaulity receiver now for $300 and sometimes less. Check out Onkyo's website for refurbished deals. They tend to have some killer deals from time to time. Also look at Yamaha, Marantz, H/K, Pioneer and Denon. Just about all receivers now are at least 6.1 but that's fine and will work with your 5.1 setup. Don't worry so much about power. Just about any A/V receiver will handle your speakers just fine.
Shinerman