To uninstall One Care open Control Panel>add/remove programs>Windows Live One Care>Uninstall. After uninstalling it is recommended to run the One Care install cleanup tool -
http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=828910&SiteID=2
Before you uninstall One Care you might try this. Open One Care>Change Settings>Firewall>Configure Firewall, expand Virtual Private Network, select Turn on Virtual Private Network. This may or may not resolve your VPN issue. I have not used this setting so I don't know if it allows a pre-configured VPN or helps you configure a new VPN but it might be worth a try.