Hi Carl, welcome.
I don't believe anyone is gonna LOL at your speakers. I used to run Cerwin Vega back in the day, which I would say are probably similar in some ways to what you have in the Optimus.
I'm gonna cut to the chase. Your new receiver is not what I would call a powerhouse. It's rated at 100 wpc, 1 channel driven. 70 wpc 2 channel. It will be lower yet when all 5 channels are being driven. Luckily, even when using surround, not all 5 channels are going to be driven at once most of the time. Your room size and listening habits (volume levels) as well as your speakers are going to dictate whether this is adequate. The Yamaha looks to have a decent set of features for it's price range and will get you through quite a few years before new technologies make it truly obsolete. That's just my opinion. I agree wholeheartedly with zieglj01, your speakers are the sound issue.
The next item I would recommend for you is a powered sub, if you do not already have one. This will help take some load off your receiver and the woofers in the Optimus and help clean up the sound. There are a boat load of options for subs priced from $50 bucks on e-bay to new car prices. I would recommend you shoot for the $500 dollar range for starters and shop and compare from there. SVS comes to mind.
After that I would recommend upgrading your mains. A quick and easy recommendation would be Ascend Acoustics HTM 200 SE's. They are priced for the budget minded and are an easy to drive 8 ohm load. The sound will be anything but hollow. You also don't have to worry about matching them for a center, because they work well for a center and rear surrounds. These coupled with a sub will bring a smile to your face when compared to the Optimus.
This is the direction I would go if it were me. The higher up the hi-fi food chain you go with each component, the more you can lessen the chances for future upgrades. As many people can tell you, upgrading can go from a hobby to a disorder in a hurry.

So to move forward from here with more specific recommendations, information such as budget, room size and your preferred volume levels are a must.