Upgrading to 8gb ram in late 2008 mbp fools errand?

Hi There,

I've just ordered some new RAM from crucial.com (on advice of an apple genius). I used the diagnostic and ordered 2X4GB RAM (1066mhz). Have i made a mistake? In some places on this forum it suggests i should only try to go up to 4gb (i've currently only got 2gb), in other posts it suggests 8gb is fine.

I'm looking for some advice - do i contact the seller and try to change my purchase or plough on with the higher capacity RAM?

Cheers!!!