I use a combination of royalty free loops, a couple of drum machines called Battery and Lm-4, a ton of royalty free sample CD's with various drum hits plus a couple of real kits sitting in my drum room.

The best bet overall is to use a combination of Free Loops and a drum machine like Battery.
You can get a ton of free loops off the net or just for a low fee (PLP Peace Love Productions... a place I'm producing loops for myself right now) offers a ton of loops as majorly low prices.

The best thing to do is what I'm doing now.
I've loaded up a whole song with several dozen loops. Then I've run Battery through a bunch of MIDI files to produce original loops.
Then I run my songs midi files through a couple of dozen synths and store all the files on a Cubase song file. In the end it looks like a huge grid.

then you can just pick and choose how you want your song to sound.

I'm gonna post links to a bunch of examples of what you can do as soon as I can get em converted so stay tuned