flash script that shows a php output every 5sec.

I have a script right now that shows when a user have a new pm. but members must update their site for them to see if something new is in. what i want: i want a flash script that checks my php script every 5sec the php script just output the numbers of new pms, like 0 , 2 , 5 or something like that and the flash script should just update every 5 sec so that they see if a new pm is up! anny questions please send me a pm!