Server noob, in need of opinion

I have a proliant 380 server, with nothing on it. I also have a 14-ds hard disk rack array, empty. I am going to wire my 5 sata 1,5Tb on this case, and true there to the server. This is the first time I come in contact with servers so i'm a total noob at it. I would like to create a storage server that:
1: is accessible to everybody of my home-network
2: is accessible by internet (like a private ftp server)
The computers on the home network are:
1 computer with windows 7
2 comuter with vista
2 computers with xp

What i would like to know is: What OS would you suggest running on the server?( preferably a system that is easy in use. I am totaly NOT familiar with linux/unix os, but maybe this is the right time to start), and if possible some specific online resources witch could come in handy when I have to set up the machine.

Thanks in advance for any direction you can give!