Have just found an interesting site, that allows you to watch the BBC iplayer,and ITV programs. Have tested a few of the programs and all seem to be playing well, just a few loading delays, but may be because my broadband is slow.
I use XP, with firefox, so cannot comment if it will work with a Mac or Vista, but you can only try.
Setup took a couple of mins and then could get straight into viewing programs. At the moment it is a free service, so give it a try!!