are you trying to resell ebox ? If so you cant make a profit off of the software at all.
If you are making it for yourself.
1ghz P3 1gb ram would be MINIMUM i would suggest.
P4 > 1.8ghz with 1gb ram would be good.
I personally use a Athlon Xp 1.8 ghz 1gb ram with 500GB HD.
4 wans 1 lan with 8 users, voip, AV scanning, proxy, and mail.