Please Help Buying Extremely High End System

[aktnine]

I have the privilage of purchasing and putting together a high end karaoke system for a friend of mine. He is the type of person who wants the best of the best. I have a $5000 budget but if i excede it is ok. Here is what I have to work with. The room is pre-wired for sound. In all 4 corners there is an electrical plug in, 16 guage speaker wire and coax cable, all run to behind his bar. The speakers will be mounted near the ceiling on the wall. He has a laptop with the karaoke program on it and will be setup behind the bar. the words will be projected somehow onto a 50" plasma on the wall across the room. He also has a 4 channel mixer behind the bar as well.I would like some suggestions on what model speakers to buy as well as what type of amplifier to buy. The amp needs to be very good and will also be powering blu-ray players in adjacent rooms. The speakers are my biggest concern. These need to be top of the line extremely good sound quality and wall mountable. I'm also not sure if coax or speaker wire is the way to go. I'm a little concerned the speaker wire is only 16 guage. The mic's are 2 cordless shure sm58's i believe. I also need to ensure that there is no feedback as he would not be happy. I really need to come through for this guy, any help would be great. Thanks.