I use a Sony Vario with soundfonts. You are trying to run before you walk here a little bit. With your setup, you need a software program to manage your soundfonts because as you rightly say, your present soundcard has no direct control over them.
Live synth pro is a good soundfont management program to get. It can be opened up in sonar as a DXi Synth and then loaded up with your soundfonts. These include some very realistic drum sounds, the thread that Moskus pointed you to is a classic method for drums.
Soundfonts are a whole subject in themselves, it will take you some time to get your head around it all.
There are also a great number of drum loops out there on the www which you can import as a wav file and then loop to your hearts content. Just seach the web for drum loops.
Fruity loops can be used as a stand alone drum synth or opened up in Sonmar as a VST DXi instrument. It too can also be loaded with soundfonts, which I also use, because as you have found out, the set range of drum sounds in FL is limited and does not sound very real.
But like everything, as Mr Argo has posted, to get a real sounding drum beat without playing the drums requires patience and a learning curve. The quickest solution is the drum loop method.
Have fun!
I know it's tough and need more patience, but that's the price we should pay. 
If you've never tasted it, try the downloadable demo version from 