Configure 2 NIC a Computer

I have two network running peer to peer using Windows XP Professional. The problem is I am not able to get on internet when both NIC are used. If I disable 1 NIC ,then I am able to get into Internet. Both NIC are configured as follows:

Network #1
Cisco Router is used as DHCP server assigning IP automatically using 10.200.6.xxx
Subnet: 255.255.255.0
DNS: 65.255.193.61

Network #2
IBM Server is used as DHCP server assigning IP address automatically using 10.172.84.xxx
Subet: 255.255.255.0
DNS: 165.2.58.10

What I need to do to make both NIC working on same computer?