firstly, the closer the samples you use are to the sound you want, the easier your job will be. the reason sound bank is a good distance away from most popular sounds, so look into sample libraries in your style.
secondly, once you choose your best sample material, there are four kinds of 'bigger' you can make your drums:
1 - wider. in order to achieve a wide stereo image in, say, your snare, whatever is coming through your left channel must differ from what is coming through your right channel. there are a few good ways to achieve this, the best of which arguably being the use of multiple snares panned left and right (and possibly a third panned center). you could also use a stereo chorus, a detuner (which could be effected by using the same sample twice at slightly different pitches and pans), or a short stereo delay set to a short value, say 20-30ms with the return panned opposite the dry signal. you can also add stereo spread to your mix as a whole by panning elements around - your kick and your snare almost always deserve to be dead-center, but other percussive elements such as hats, shakers, or toms can be moved off-center to occupy more space in the stereo field.
2 - taller. your entire drum mix should occupy most of the audible frequency range, with the lows very low and the highs pretty high. if your snare is dull, use brighter hats for example. the same applies to individual drum sounds - if you want your snare to sound taller, beef up the body by adding some EQ boost to the low mids and brighten it by adding some boost to the highs. kicks can be made taller by layering a sub bass sample under your main kick (make sure the bass frequencies from each don't overlap or you will get interference).
3 - deeper. your drums will appear to occupy more space if you add ambience effects, even if they're almost too subtle to notice. add some room reverb to your snares and hats (i prefer not to reverb the bass drum - your mileage may vary). you can play with stereo delays depending on your style - try either a tempo-synced delay, or a very short delay time so that your delay returns do not interfere with the rhythm established by the dry drums.
4 - more powerful. there's an importance between loudness in the sense of peak amplitude and loudness in the sense of average power over time. the use of an auto-gain compressor like those which come in reason can decrease the dynamic range of your drum hits and therefore increase their overall power (in the amplitude-over-time sense). however simply reducing dynamic range is not sufficient to deliver the psychoacoustic sense of 'power' as we experience it subjectively. compression is an involved science that will take some time to master; tutorials abound on the net - take the time to research how to apply this effect to suit your style.
