I have the exact same bike... a college roommate used it for riding to class and gave it to me (or sold it cheap, I don't remember) when he left.

I have the same paint scheme, but it's not in as good a shape.

Mine came with the same shifters, but a really lame Huret rear derailleur. I'm guessing yours had the same rear mech, but a previous owner (wisely) binned it.

I also had a (Suntour) five-speed freewheel, but the spacing is 126. My freewheel had very WIDE spacing between the gears. Same Sakae crank, but 46/36/26 with a Biopace middle ring.

I gave it a whirl as a fixed-gear conversion, but never really fell for fixie fever.

Recently, I upped the freewheel to a six speed, put on an RSX rear derailleur and 6-speed SIS downtube shifters. Also put on some 27" cyclocross tires... haven't really ridden it in that setup yet, though.

I have been thinking about totally repainting the frame and building it up with STI RSX 7-speed stuff off of my wife's bike. But I don't know if I like it enough to do that.

Interestingly (?), I also have a Centurion Sport Dlx. So all you need is a CAAD4 Cannondale and a Gunnar Roadie, and you can be as cool as me!