It seeems that gymrats struggle with the issue of abdominals (or more commonly referred to as abs). These muscles, which in popular parlance also include obliques, are either overworked (by pathetic novices that believe in such a thing as "spot-fat-reduction" and/or completely neglected -- by equally misinformed lifters that believe that cardio alone with reduce the fat and build the region. Does cardio alone build your pecs? NO! So where on Earth did you get that cardio would build your abs and obliques?
The reality is that abs & obliques are our CORE MUSCLES, but that actually means something folks. It means that these key muscles keep everything together, they are employed when you stretch (to warm-up), they are employed when you bench press, and they are employed when you're running, swimming, and more than likely when you're having sex (though from the looks of you some of you, prolly not -- KIDDING!)
The key to developing a strong, defined core --- like anything else, is finding that reasonable middle-ground. Train these muscles at least one day per week - shying away from heavy weights, which will only make your appear denser and more bulky! Focus your efforts on range of motion and strict form -- if ever there was a need for finess -- it would be here.
Good Luck!