[PROBLEM] xbian turn off guest access?

[swinxx]

hello!

i have installed my newly aquired raspbmc media center with xbian.
great!

when i connect from my mac (with the finder- connect to server) to the rasp, i can use a guest account. i want to turn that off and instead want to create a dedicated user.
can i configure that within xbian?
if yes, how?

thx sw