Ok - these instructions assume your router isn't a wireless one (if it is, you'll need some extra configuration to make it act as a wireless access point in stead of a wireless router).
Firstly, you need two network interfaces in the PC you're going to use as your router - one for the internet, the other to share it with your network. A network card can be purchased for under $20 AUD (probably less in the US) and is reasonably easy to install. You could opt for a USB network card if you want to make it really easy or if you can't install a normal (PCI) one for some reason, but these are more expensive. If your modem has a USB connection, you can use that as your first network interface and your existing network port as the second (no need to buy anything :-) ).
Once you've installed the second interface (if required), set up the internet connection on your nominated PC as you would if it were the only computer using it. Use either the USB connection if available, or one of your network adapters.
Check you can surf the web and don't proceed until you can.
Next, you should be able to use your router as a switch (a box that connects your computers together). It will most likely have one port for the modem/WAN/ADSL (labels vary), and probably 4 others or so for computers on your network. You won't use the port that connected to your modem/WAN/ADSL any more. In stead, plug your computers into the other LAN ports on your router (they may be labelled "LAN").
Now we have to share the internet connection. Click Start, Control Panel, Network Connections. There, you should be able to see your internet connection and the extra network interface/your link to the other computers.
Right click your internet connection and click Properties.
Click the Advanced tab
Tick/check the "Allow other network users to connect through this computer's internet connection" box
If you have an option to choose a "Home networking connection:", select "Local Area Connection"
Click OK - if you're still connected to the internet, you should be told that the changes won't take effect till next time you connect.
Restart the computer and say a prayer (this is a Microshaft system after all ;-) )
Connect to the internet on your computer
Check your router is on and all your network cables are plugged into the "LAN" ports and NOT the "WAN"/"ADSL" port (there should be nothing connected to this port).
Try to browse the web on other computers.
Hopefully that works - though there are some strange quirks with this sort of thing. Let me know if it doesn't work and I'll give you some troubleshooting tips.
Once your internet sharing is working, set up the PC you're using as a router as a VPN server using the instructions mentioned before. That should give you:
1. Remote access to your network from home
2. All PCs at work available to be used during remote access
3. All PCs at work able to use the internet
This isn't a really secure solution by itself by the way so be aware of that. You might want to install something like Comodo Personal Firewall on the router-PC, which you can get for free here: http://www.personalfirewall.comodo.com/ .
Post again, possibly in a different section if you want instructions for that - it will require some more advanced configuration.
Regards,
Chris Fry
Canberra, Australia