Firewall configuration with two ISP

["Bala" <balamurugan@runbox.com>]

Hello
  In Debian GNU/Linux, I have configured three network cards. I'm having
leased line connection from two ISP's with two different series of IP
addersses. With first card I, have configrued ISP1 and with second card, I
have configured with ISP2. With the third card, I have configured my LAN.
Now I'm able to ping both the ISP's gateway from my machine. But, I'm NOT
able to access my machine with one of the Internet IP from Internet. What
could be the problem??

Thankx in advance
Bala