Good replacement for AVG Anti-Rootkit Free Ed.

From my sig you can see what else I'm using. I like AVG and chose their rootkit program because it was free and because I was already using their anti-virus and anti-spyware programs, so I figured compatibility issues would be minimal.

But now they've stopped offering updates to the Free edition, so I suppose I need a new anti-rootkit program - I'm looking for one that's free and effective. Small size, fast speed, no compatibility or CPU hogging issues would be a plus.

Any recommendations?