My own Hardware Appliance

hi !
Since last year i have successfully installed Proxmox and Endian UTM and Zimbra. A full e-mail, firewall and virtualization solutions for some clients.

I would like to go further and provide them with a Hardware appliance. I have checked sites like

http://www.linuxappliance.net/

but would like to know your oppinion into building my own Intel compatible Linux hardware appliance.

thanks !