SWFObject: using ExpressInstall

Hello:

As I understand it, I would use the ExpressInstall parameter in SWFObject:
so.useExpressInstall(‘expressinstall.swf’);
if Flash IS installed on the user’s browser and their version < my version.

Can I also use the redirectUrl attribute:
so.addAttribute(“redirectUrl”, “http://www.example.com/altcontent.htm”);
to display alt content if Flash is not installed/disabled in browser?
Or will it always go to the alt content?

Thanks.