Windows VPN Assistance

Any of you geeks know jack about VPNs in Windows XP? My boss is trying to get us set up with VPN for some filesharing and we are having a bear of a time. And it’s not because we’re Luddites – my boss is a grade A uber-geek. We’ve been Googling and tinkering for two days now. If you have any contacts/info/know-how, let me know!