FL Studio is pretty good if you have access to some decent samples. The included drum samples are way too dancey for me.
There's a free program called (I think) TS404 which is really cool, again, if you have access to some decent samples.
there are tons of free samples out there to be downloaded. (Goes and checks Bookmarks...)
There're a billion drum machines sampled here
http://samples.kb6.de/downloads.php