firestorm is good, but if you're shelling out for it, I'd say it's not work the money. Plus it's quite hard to personalise the sounds cos they're all so heavily processed.
I'd say, get you're self a couple of breaks and some decent single hits and start chopping. Vengence club sounds has got some meaty drums that and useful, and you can get all the decent breaks for free over the internet. I'd say the useful breaks for dnb are:
Amen (obviously!)
Hot pants
Do the Do
Think
Apache
Worm
There are literally hundreds, but those ought to get you started