two connections

Hi,
I have a PC running XP Pro. Due to the slow connection to
the server (ISDN), I have been trying to set up a second
nic card for the internet through a cable connection. I
have to use the ISDN when 192.168.102.156 connects to our
server for retail information. I want the second card
(cable) to connect when the internet or e-mail is being
used. I can get the internet on the ISDN connection but it
boggs down the retail information for the store. If I
disable the ISDN, the internet comes in fine on the cable
connection. Our emulation software uses whichever card has
the metric set to one(1) this doesn't help as IE does the
same. How can I tell IE to use the second NIC card????????
thanks,
Brian