I used autokiller for awhile. It's nice because it's not actually a task killer, in the usual sense, and it uses the stock Android algorithms for optimization. However... I quit running it, and didn't see a noticeable decrease in performance. With your older Droid, you might see a benefit. I had mine set really aggressively, I never had less than 150MB of RAM free.. But I also have 512MB vs your 128(?). I'd say install it, mess with the settings, see if it makes an improvement for you. If not, lose it.
