E-510 for theatre work?

Probably have to use my (tryout) E-510 shooting at a professionally lit theatre in 2 nights time where I expect it to work well. My question is: most of my theatrical shooting will be rehearsals NOT under performance lighting but ambient, high lighting on a black floored & curtained stage. Is the E-510 going to be the camera for me...I hope to stay at or below ISO400.
Would appreciate a quick response....starting to panic:)

Eddy
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My motto: Photographers should be seen and not heard.
FZ50, UZI, B-300