Client side vs server side?

I'm still new at this, so please be patient but also explain with as much details as if I were a retard:



If I want to make a chess program for a forum where forum members can play against bots (this is theoretical) ... if I understand this right: If I use something like php or flash, all the work will be done on the server, but if I use javascript, the calculations will be made on the person's computer?



So if like 100 people on the forum are playing the game at the same time, the flash chess game would cripple the server while the javascript one wouldn't since all the AI (pc intensive stuff) is done client-side? If I go with php or flash in such a spot, is there another way to have the AI done client-side? maybe with a java applet which is seperate but all it does is the AI while flash is there to make it look good?Client side vs server side?
You have it slightly wrong.

Flash is a client side technology. It is also considerably faster (by a A LOT, especially in IE, which is slow slow with javascript).



Another alternative to Flash and Javascript for client side is Silverlight. Silverlight is still sadly immature, but of the 3, it has the best programming model for writing chess algorithms.



Client side Java is also an alternative. But it requires the user to install Java. Lots of people seem to stumble over getting that done (How do I install Java is a common question here....although sometimes what they are asking is...how do I turn on JavaScript? Very different answers).



If I had to solve that problem, My choices would be (in order of most viable):

Flash (Flex)

SilverLight

Java

JavaScript