Remote POS software (real time sales on the road)

I need to set up a system for my fathers company that will allow them to make sales via a VPN over cell internet access on the road. I'm not sure exactly what is needed, but I understand the theory of how such a system would work. I can't think of any examples other than the system that Snapper tools uses; they have laptops in each of their trucks and (I'm assuming) via a VPN and verizon wireless card, they connect to a server in an office somewhere that processes the sale and subtracts sold items from a DB. More or less it works like that I'm assuming, but while I'm pretty sure I know how to set up the hardware side, I'm not so sure about what software I'll need, where to get it, and what all is available.

I know that quicken makes software for DB management and sales, and there's peach tree software as well, but I don't know if any of these allow for POS via remote access. Has anyone here worked for, or currently works for a company that has a similar system in place that would could give me an idea of what I'll need? I'm kind of in the dark here, so any information would probably be useful.

Thanks

Just give me one more chance at the top Johnny! I promise, I'll do better this time!

and then there was bump-age...and it was good.