At a client's office, their SonicWALL device is out of commission temporarily, so I've set up a Linksys WRT54G router in its place until we can get a fix.
They need some kind of VPN solution, though, for access until the SonicWALL is back online.
What is the easiest way to get a VPN setup configured between Windows Server 2003 and Windows XP client machines? I was thinking of something like Hamachi for the time being, but I'm not sure if doing it natively with Windows is easier...
RRAS's VPN is pretty easy to setup. Here is a guide.
I'd go with Windows RRAS, its very easy to setup and manage, supports both PPTP and L2TP and RADIUS if you need it. The only significant downside is that if your running it, you can't run the windows firewall, but that's not always an issue.
You could flash the WRT54G with DD-WRT and run OpenVPN in static keying mode.