I know people that have had WRPTool 9.50 running fine on Win 98, I was for a few months!
It supposedly doesn't work because of 'memory errors', but it worked fine for me!
Sure, it may take a moment to load and save the WRP's, and the minimising between OFP and WRPTool is slower, but in the long run it is so much easier than WRPEdit or Visitor! Plus the documentation and support is greater. WRPTool has a really easy interface and feels like a professional program...
I could be wrong here, and you've already tried with no success, but if you haven't, give it a try!! Download it. If it does work you will save so much time, providing you have a decent amount of memory....