I'm not sure I can help exactly but...
I use Garageband on my Mac, I've got Cubase Le but it doesn't seem to come with any drum loops (Please correct me if anyone uses this!) and I haven't been able to set it up correctly (an ongoing issue!)
Garageband has some ok drum loops, and I've got others from free cds and you can download some (try free drum loops in google). The thing to bear in mind is that lower end software often cant time stretch mp3 or wav files very well so midi files may be more useful (but you'll end up with the cheesy drum sounds of your software).
I prefer to find a good groove from the loops I have and use that at the tempo I want , get a good tune down and recorded and hope that someday I can get some better drums to replace the originals.
In other words, don't let the drums stop your guitar playing, that should come first. After that you can get BFD or Drums From Hell to beef out your sound.