Encrypted disk on a server

[skx]

I have a headless FreeBSD server at home serving as NAS, http server, 
proxy, vpn server, etc. Due to the way network infrastructure is 
organized the server is located in an easily accessible place (actually 
outside my apartment) and I am afraid it might be stolen. It's a cheap 
old PC, so I am mostly worried about data stored on it. 

What is the most convenient way of securing this data (besides moving the 
machine :)? Encrypting the whole disk? How would I provide the password? 
I am not a geek, so I would prefer a how-to or an easier solution than a 
lightweight sshd on /boot about which I read on the web. Maybe 
encrypting /home is enough? How to move current installation to the 
secured environment? 

-- 
skx