Custom Chat Client

Need to design a Chat room Client or clients - we are looking to have a chat roon that our members can enter through our site and interact. we wish to have a programme or chat client that allows us or the users to attach/assign sounds/wav files to certain words , or even maybe emoticons. We can pre set the words and sounds - so if i were chatting with someone in a chat room - i can use and send certain words and these words when they arrive on the other persons computer will emit a sound or sounds. It will need to be quick and effecient - we would like to consider MSN add on perhaps So to refresh , i need 1 A chat room that multiple members of our services can log into and use 2. The chat room will have private room options and allow say up to 8 people to chat ? Is this possible ? 3. When chatting with someone when i send or use certain words or emoticons these words will when they arivve on the others users computer will thyru the speakers emit a sound - wav file 4. We wat to perhaps be able to fine tune this once the basics are in place