Networks Access... Can I use IPv6 for LAN and IPv4 for Cisco VPN

Dear Fellows,
I have a problem in Networking. scenario is,

1 - Earlier we had 3 XP computers connected through switch and sharing files and printer on switch too.
2 - We had to connect to wireless network for internet which was mainly used to connect VPN server for outlook exchange server (VPN for emails only) it's Cisco client with IPsec/UDP.

We used NETBEUI protocol for file & printer sharing on local network and TCP/IP for VPN. Even after connecting VPN access to local resources were there through NETBEUI.

Now we have Win 7 on one machine and it does not work with NETBEUI. AND after connecting VPN local access is gone.. I tried installing NETBEUI but it access computer with \\peer\DB path BUT not showing all folders and files. ???

1 - My Question is "Can I use IPv6" on LAN adapter and unchecking IPv6 from wireless VPN adapter, so that IPv6 not handled by VPN server and allow local traffic.. I don't know much about IPv6 and need beginner help to add manual values in ipv6 settings.
2 - Also will other XP computer share on IPv6 ? Win 7 does not need to share anything but XP to share.