mandible 0 Newbie Poster

Our application has a requirement to use a ShowModalDialog box functionality. We have just phased out IE6 and now can develop towards IE8 functionality.
From what I can tell ShowModalDialog works still and that's lovely, but I believe it's deprecated and therefore doesn't support some of the newer functionality of IE8 ( our users are allowed to use the Text->Larger option which does not seem to be supported in a ShowModalDialog ).
I was wondering what the current recommended trend would be for this sort of functionality in IE8. I'm thinking an in window popup that fades out the background is something I have seen in newer browsers but I'm not sure if that functionality works in IE8.
Is jquery the way to go? or is there a more integrated into the IE8 platform option?