Hi,
Having had some problems installing the update recently (I suspect due to hardware probs was having at the time), I was pointed towards the FSUIPC forums where Pete Dowson mentioned that in some cases it does seem to hang but in reality is still installing and just give it time even up to 20 mins. Apparently some systems just take a long time. Whenever I had problems installing it told me it had crashed so if not getting that message then I suppose give it time. Sorry can't find the forum link.
Phillip