hi..
i want to develop a collaborative online whiteboard, (two or more users can use the same whiteboard to paint the same thing), i want to implement it in flash and php using xml socket, but i am getting the impression from many tutorials on this subject that php is not good for multiple socket connection because it doesnt support threading, can anyone help me, is php the right tool or should i use something else like java ?

Um, not that I know everything about PHP, but I'd suggest looking elsewhere. Flash & Java areas may be better for this question (I don't know either).

A java applet or flash app would be better for this kind of thing. You can still use php as a backend to handle database info and other things but I wouldn't know how to approach this with php alone. I would look into java personally. I am a Java programmer but not for web... I've never done more than play around with applets but as far as just plain java coding goes I can help you out (post in the coding forum if you have java questions).