It is a pity you dont own a Volt meter.. if the Bat is reading about 3V .. all is well with it.... if lower than 3v. return it to the place of purchase as an enema.. (lol did a google.. and found this.. http://glum.no-ip.org/enema.html )
I am assuming the warning regarding the battery was coming up during POST.. Just check in your Setup.. there may be a setting for that alarm.. particulary the voltage to trigger.. may be set to 3.02V way too high.. 2.7-2.9V should be plenty high.. Just be sure that your looking at the battery alarm not the memory or AGP voltages or you will Fuxor the mobo..or vidcard..
"Consumer technology now exceeds the average persons ability to comprehend how to use it..give up hope of them being able to understand how it works." - Me http://www.cybercrypt.co.nr
are you sure that you seated the battery on its proper manner?
Try to reinstall the battery on its place...
It seems that you repalce it but you didnt check if the battery is fix on its place, it shouldnt be shaking.
It might be the battery is not inserted properly... try to see again...