Hi,
here is my 2 cents. It sounds like you need a new crank. The Sugino cranks are cheap, and will prob work with your current BB.
If you want an upgrade, you can get an Ultegra crank here on sale
http://www.jensonusa.com/store/produ...+Crankset.aspx
It will need a splined BB. This you can use for your current gears, or you can upgrade to 8 or 9 speed. This will require cold setting the frame.

That means you need to go to your LBS, and see what they think.
You don't want to mess up the chain line. You can also ask them if they have an old 7 speed road crank in the cellar they wouldn't mind selling. Most bike shops do. Heck, everybody has one.

I wouldn't go nuts over Superbe cranks. I used to be a Suntour fan back then. But the prices have gotten nuts. What would be worth spending a few bucks on are some nice new wheels.