Some analog NEWBIE configuration HELP ... please

Hello all,
I have done much research and set up a small * server in my house just with VOIP. With that said, I have a setup for a buddy that consists of 15 computers, 15 analog lines (heavy call volume technical support company). He wants the * system to have more features than he has on just analog, such as supervised transfers. They hav just ADSL, so i was thinking of adding a few lines there if needed overflow.

So here is my setup with much thought.

<15 analog lines>—<rhino 24 pt fxo channel bank>—(T1)——(ETH)—<15 linux workstations with softphones (SIP)>

will that work?? If I need to use the DSL for VOIP can I go out another ETH card from the asterisk box?

Thanks in advance