I'm have a pc/server with ubuntu 11.10 installed and I wish to use it as file server and media center

I installed this program called Webmin to easily remote administrate my samba settings(and maybe web server in the future) also I want this server to act as Media center, so its stationed near my tv and connected using the vga input on the tv, I managed to get the the media center software(XBMC) to work but I can't get samba server get up right,

I used a windows pc and a mac to try to connect, the windows pc gives me a error right away when selecting the server in the network folder, and on mac, I can login, and pick a shared folder, if I want to open that folder it does noting and after 10 sec it gives a error that he could not find the original folder.

Can someone please help me?