Search engines. If you have any money to invest you can buy all sorts of sound sample packs via the internet. Alternatively, if money is an issue: Sample the sounds you want directly from tracks that you hear. There's quite a few isolated kick drum samples in the EP above, for example.
itsclipping.org/category/free/ (currently on holidays) itsclipping.org/ will be back online soon I'm sure.. IC is one of my best mates so I can assist in firing up the apache server...
