you only need 1 arduino
click playground
output
direct driving of an 8x8 grid.... the schematics are there... you just have to extend the multiplexing to a bigger grid.
if you really want to go with luxeons, check out thingm... blimkm, it might be more your speed
http://thingm.com/products/blinkm.html
full rgb luxeons, and they use spi, so you can just daisy chain as many as you need..(actually I think 256 of them... but don't quote me)