NFS UDP MTU

[Charles Darwin]

Hello to you all,

I have a question about sharing a directory over my subnet. I have  
users downloading up to 3-4 G per session and obviously speed is  
crucial. I am thinking of going with UDP (accuracy is not an issue  
here). What is the best way to go about this? Is NFS the right pick?  
If so should I use mount_nfs, ar there better utilities available? How  
about MTU; do I need to tweak the value for MTU on client machines?  
and if so what is the magic number?

Thanks,