I have an intel iMac from 2006 and Silverlight works fine, but I have not updated in a long while, so if there is a new bug I wouldn't know. It may have started working even more smoothly as well.
I don't have a problem with Flash on Hulu, either. It used to take much more CPU power, so the computer would be unresponsive for a few seconds after stopping the Hulu stream. They must have optimized the site since then, as that does not happen nowadays.