ISA SERVER INSTALLATION

Please tell me what are the things i have to consider before installing ISA server and tell me step by step procedures to follow while installing ISA SERVER and how to configure it on server and client pc.
One more request in my network clients are going to connect internet through this ISA SERVER and my ISA SERVER is going to connect internet through Dial-up using modem
Next thing is i want to make the setting in such a way that if any client request for internet connect to ISA then this server should repond to that client and make the connect even after there is no connect means DIAL ON DEMAND.

THANKING YOU IN ANTICIPATION

I REALLY REALLY THANKFUL TO YOU GUYS.

BEST REGARDS