Please help me...I have been Googling for hours!

I have two computers...Ubuntu server and Windows XP client. Both are connected to the internet using Ethernet. I have them connected directly using 1394 to increase speed of large transfers. The internet network and 1394 have different IP address scemes.
Internet 192.168...
1394 10.0.0...

I am having problems getting the two computers to communicate with each other. I can ping the server's ip address and and it loops back. Same with the XP's IP address. I can't ping each other.

ifconfig shows my eth0 and eth1 connections are up. The eth1 Link Encap says UNSPEC. (Don't know if that means anything.)

The connect used to work and I have no idea what happened to break the two.

Thanks.