Hi Steve
I also have these speakers hooked to my iMac 20" Intel Core Duo, and they sound OK, considering the size of the drivers on the satelites (about 2").
Small speakers have small sound, regardless of the brand (even the Bose), and it's an acoustic limitation.
These JBL have a crossover frequency of 180 Hz, in other words, the satelites MUST start responding well at 180 Hz which is kind of difficult.
But for general use, I think they're pretty reasonable and well balanced.
I also paid $44.00 for mine at eBay (refurbished by JBL), and at this price, it's a steal compared to the rest that's available on the market.
Good luck.
Pedro