If you're not putting several hundred pounds of force into those cranks, something is wrong. Either get a new bike, or get
a quality BB like Pauls. Ever try Sugino? They make a nice crank that's cheap. There's a nice french brand of crank that might be a little tougher than average.
http://www.peterwhitecycles.com/zephyr.asp
The new formats like Isis will prob stick out so far it twists your chain out of line.