Help please, I need to find free software to create drum tracks for songs. Anyone know of one?

Hi, I'm trying to write some music but need to find freeware for creating drum tracks to play along to. I have used an old version of cakewalk years ago which was brilliant with the grid system laid out, and something like that is what i'm trying to find now. All I need is the drums, and I'm playing rock music so I imagine jungle samplers and the like aren't much good to me. Thanks!!