Yeah that's a common problem I believe (it's a game problem, not a problem with the fix). They released a patch (filename rct-us.exe or rct-uk.exe) but Atari doesn't seem to host it on their site anymore. You can download it from
Fileplanet, though.
You'll probably need to patch the original unmodified executable, and then use the widescreen fix on the new patched file. I know it solved the problem in XP but I have no idea if it will work with Windows 7 or Vista.
Good luck.
Oh and I don't believe the patch works with the two expansion packs. Either they included the fix or they never bothered to patch them.