ALL IN ONE S.E.O.

I want to ask whether “all in one s.e.o plugin” is compatible with word press 3.1 if not then which is the best alternative. Moreover I have installed Greg’s s.e.o pack but when search more on this plugin the report is not good. PLEASE TELL ME CAN WE USE TWO S.E.O PLUGINS at a time. Is it good or not? and what plugin should I use to get the maximum results.