I didn't want to setup an ftp server for filesharing with friends. I started an SSH server, this is working fine now. Is their any difference in performance? I.e. is FTP faster because it's an different protocol? I want to setup an user group who can only look at the files and download the files of one specific download folder. So they login and the only see the downloadmap, is that possible?
And what kind of uid do i have to give my friends? Anyone got some tips how i can arrange these things?

Thx in advance

Well one main difference is that SSH is a secure shell. So your giving your users a shell access to your machine. FTP, you can limit their access to any particular directory or files with no shell access.
SSH is secure, regular FTP is not. There is however secure FTP programs out there. SSH is more of a utility of remote access and administering your machine as I see it, not for transferring files and such.

Oh and your won't see much of a speed difference between the two.

Because it's secure i wanted an ssh server instead of an ftp server. I already transferred files from my box to school with WinSCP and it worked fine. But now i want to setup an special user group with only one downloadfolder, and further no browsing rights, only the downloadfolder

Here's my suggestion though:

You may want to setup a secure FTP server then. Its easier to setup, it doesn't allow any user shell access and you don't have to mess with changing all the permissions and groups, etc on your machine.
Giving your users a shell login account so they can SSH into your machine still gives them more power then what they need to do if they only need to either upload or download files.
But other than that, if you still want to use SSH, I would suggest creating one account that they all use the same username and password with, and only have access rights to the one directory you setup for them.

Thx for the advice, looking for how to setup an ftp server right now. Currently one friend is downloading a divx through ssh and it it is working fine, if he removes something i just have to kill him . Will try to setup later an ftp Thx for the advice