Thanks for the guide. It REALLY helped!
A major omission though. With windowsXp you must either turn off the firewall for your local net or better yet add mach3 and gRexloader to the exempted applications.
I just had fun trying to figure out why on two nearly identical computers, one worked completely and the other couldn't run gRexloader or Mach3 but could be pinged, and amazingly successfully loaded with firmware and fpga code from IE using the IP address. The G100 was setup about 9 months ago on the first computer and still worked.
I had seen a post about the firewall but the firest machine worked fine with it enabled. Both computers had the firewall enabled with the same port and application exceptions on both so I didn't think the firewall was the problem. gRexloader and Mach3 could never connect to the g100. As soon as I disabled the firewall it worked. Adding gRexLoader and Mach3 to the exceptions and enabling the firewall also worked.
I can only figure that some of the windoz updates that have been installed in the last 9 months somehow allowed the existing setup to work but when I built the new system the firewall had to be configured more strictly. Hope this helps someone.