Assuming that Denon has DTS/Dolby Digital support, it should do you just fine.
I dont know much about those Optimus speakers. Assuming you arent an audiophile though, they should do you fine.
Could you describe the subwoofer more? Does it get its input from normal speaker wire? You say it doesnt have RCA, what does it have? The subwoofer is a very important part of a home theater, you want to make sure it works.
Oh, and I would have posted this in Tilted Entertainment