32/64-bit XP and Windows 7 64-bit networking problem

[chalkmaster]

I have 2 computers same specs. My partners connects to the internet(broadband) through my PC. while my PC has windows XP32bit running. Platforms Xp32 Xp64 windows7_64bit all connect to the internet on my partners through my PC OK. But only if I run Xp32bit. If i change my PC to 64 bit... hers will not connect to the internet no matter whether hers is 32bit or 64. I have uninstalled firewalls so I know the problem isnt them .. It says it cant get an ip address when i try to resolve the issue with options available. Any ideas would be most appreciated.