VPN problem

Full disclosure: I run my boss's network because he barely knows how to right-click, not cause I know what I'm doing.

We have a router which our isp's T1 goes into. From there, an Ethernet cable runs into a Hawking H2WR54G wireless router. Three PCs are hard-wired to the router and one laptop accesses it via WI-FI, via the Hawking when in the office and via a EVDO network card and VPN remotely. They are all running XP and are all on a network.

The two routers didn't communicate well (I guess this is an ineffective setup, but I inherited it), so I configured the Hawking, under our isp's direction, to work as an access point - plugged the cable coming in from the isp's router into one of the LAN ports instead of the WAN port.

It worked fine until a few weeks ago. We lost our Internet for a few hours in a storm. When it came back on, the main PC which we need to access with the VPN had a different IP Address. I mapped it as a network drive on the laptop and it worked fine for about a week.

Then I started getting "network path not found" errors. I tried all sorts of different settings on the PC, the laptop, and the Hawking, but nothing works. I tried going back through the WAN port, too.

Our isp (CBeyond, by the way), says they can see and ping the PC via the VPN, and they think it has something to do with the Hawking.

What do I have to do to make this work? If we have to buy some other equipment, like an access point, that's fine. But we need three PCS hardwired on a local network and the laptop wireless via the EVDO network card, and ideally via WI-FI in the office if possible, as the network card and VPN are very slow.

If you can help me to get this function, I'll be eternally in your debt. And if you're horrified by our ridiculous set-up, I apologize. Like I said, I don't claim to know what I'm doing.