Does anyone know of a decent N64 emulator for a modded x-box?

surreal64, or project64 one of those has 3 other emu's with it and will pick the best one depending on the game.

do you know where to get them?

well don't forget that only 4 nintendo 64 games work on the xbox unless you get the RAM upgrade. The xbox's 64mb of memory just isn't enough to play 64 roms correctly.

well rephrase that by saying that pretty much nothing works perfectly, some are goofy but still playable. but some are completely unplayable probably the reason your getting it anyway.

ill do a ram upgrade though for a $150. its something like 250 tiny ass solder points

You couldn't pay me to do that... WAY TO MANY POINTS!!!