VPN for small work group

I have a very small peer to peer workgroup at my UK office. One machine running Windows XP which is essentially a client and one which holds most of the data and is basically the server. The XP Pro machine holds Lotus Approach databases around which my business is constructed. I have a Windows CE netbook and an XP Pro lap top that may also end up in the office or I may replace everything with thin clients and two servers if someone can convince me that Approach will continue to run.

I have an office in Russia running three machines, two XP and one Windows 7.

I want to subcontract data entry and other work to off site workers.

I need a VPN. I only need a single channel VPN most of the time. In principle, XP Pro contains a single channel VPN. I have even made the VPN on the laptop work. However, VPN on the "server" which holds the data does not work. It does not work even when VPN'ing itself. It is an early version of XP supplied by Mesh.

So, can someone provide me with software to add one or more VPN channels to my XP Pro. There is a firm in Bristol that used to sell this but I have lost track of them.
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Clarification

The host for the database, which is the only site that needs an incoming VPN has 512 MB broadband and a static IP address. The router is an eTEC wireless router. The peer to peer network behind the server is presently two machines but may go up to 4 machines. I am open to replacing the router.

The Russian site is effectively 56 KB dial up. Other external connections may by on iPods, iPhones, iPads and PC in various locations.

Please note that the host "server" although Window XP Pro does not work with Windows Remote Desktop. It also does not work when the outgoing VPN on the machine is connected to the incoming VPN on the same machine. There is presumably a switch deep inside Windows XP which has not set properly.

The Windows is Version 5.1 Build 2600 xpsp_sp3_gdr.101209-1647 Service Pack 3 originally an OEM version from Mesh. Mesh rebuilt the machine a few years ago.

XP works for me. I intend to run it until it is well past final support.