First, you should definitely take a look at the "seperating frequencis" thread. It deals with much of what you ask in this question.
To give a short answer to the question:
Pick another sample. One with more bottom. If you would like a couple of my faves, I would be happy to share by email, just credit me in the liner notes... just kidding!
If you are stuck with the current sample that you are using (meaning you are not going to replace again....hopefully you are not doing by hand!), then you need to decide what needs to be done the current sample to make is sound like what you hear in your head. What helps me sometimes is to look the frequency analyser curve of the hit. This gives me a visual of what is happening. My usual is, cut deep lows (25-30 hz), boost in the 65 hz range for chest. The sample should have enough snape already. One caveat, I am a Brenden O'brien, Andy Wallace, and the Johns family, fan so I am shooting for that type of drum sound (which I never get). Without knowing what you are referencing, it is hard to know what direction you are trying to go. Low on a Jeff Buckley Record is not the same as low on a Linkin Park record (or maybe it is?).
j. armstrong