It partly depends on what version OS you currently have in the Max. Take a
look at the "Ugrading system software" section of the following file:
The best way to do it is via a direct console connection. The TFTP server
can be anywhere and so can the OS files, so long as they're accessible via
the net without much traffic).
I'm using 6.1.0 on my 3 Maxes and haven't run into any problems. I've
heard that 6.1.3 may have a couple problems, but I can't speak from