From watching friends, and from personal experience, I can attest that attitude is far more important. from honest, actual feedback from several women, (albeit in the 18-25 range) including one I am now engaged to, it seems that many women aren't fond of six-packs and rippling ab muscles, at least in a relationship. Why?
One, they aren't as fond of the look as they are of a simply smooth, toned stomach. Second, a little fat on your abdomen is healthier- having 4% body fat is actually considered to be a dangerous, so as long as it's not to a point of being morbidly obese. Third, they like the feel more. While having rock solid abs is impressive to them, and demonstrates a certain level of physical fitness they like, they want some fat there so that if they're cuddling or laying their head there they have some cushioning between them and the steel that is the well developed muscle. Fourth, having an incredibly cut, muscle bound physique means that you have to spend a fair bit of time maintaining that look. Do you really think they want a long term relationship with someone that's going to have to devote time to that process, in addition to the time they have to devote to work, and time for whatever else they do, and lose the time that they may spend with their significant others, or, down the line, kids?
And no, these opinions have not been given to me because I'm insecure about my current build. I'm one of the group that has rock hard, but slightly covered, abs. If I tense it, you can actually see the muscle defining itself past the fat. However, I've been told (by my fiance' and several good female friends (not that sort, you dirty minded people)) that I am, under no circumstances, to deliberately try to lose that fat.