Filesystem will automatically lock files from write if they're already open. You can't override this remotely though so if someone opens it in the shop and goes home, you're stuck with read only unless you can get to the other computer.

Better solution may be remote desktop to the computer where the files are.

You don't technically need a VPN, just port forward the router to the machine you want to remote desktop in to so that port 3389 goes to that local IP address.

You need static IP on the shop internet connection as well.

If you want it more secure then a VPN is a better solution but lots more messing. The Netgear DG834 will support it if you have recent firmware. Anything after version 2.10.22.

I also wouldn't recommend trying to share files over a wireless link. The important stuff that you need to get to should be wired to ensure its always available. Wireless, particularly in a workshop with loads of metal all over the place won't be fantastic and if you're not there you can't twiddle.

Good luck :D

Right I have been asked to set up a wireless network at a workshop.

Im sorted on setting up the wireless network as its just a case of getting a modem/router and setting that up. No big deal there!

The problem is that the customer wants to be able to access some files in Excel etc from home so I need to know how to VPN in and if its easy to set locks on the file so that if there is more than one person using the file there will be write locks etc applied to it.

I was going to get a Netgear wireless router but I dont know if they support VPN.

Im really entering new terratory here with VPN so if anyone has any links to good basic write ups about it I would be thankfull for them.
Also if anyone has any routers/modems for sale that would do what Im after then please let me know!