Dan,
I would say not trust what you hear in your headphones as an accurate example of what is being recorded. It reay depends on the headphones, and some other stuff. I have 2 pairs of what are considered "decent" headphones for recording and they both sound very different.
In the end, unless you have a VERY accurate listening room (not too likely in most home studios), you should listen to your recordings in lots of different places to be sure of what you've got. Start with listening in the open air through your monitors. then try it in your ipod/mp3 player, then in your car, etc. Once you've done that a few times you should have a pretty good idea of what to listen for while recording. If you have decent monitors, you can also get a pretty good idea listening through them at a very low level (not WHILE recording...just after), to downplay the room's effect on the audio.
Good luck.
Ken