I found out that Windows 98 isn't compatible with high-speed cable internet! No wonder the speed was just a little faster than dial-up. I now have to get Windows XP for it to work. Do you concur with these conclusions?

Cable internet will work with Win98 [also Win95 for that matter].
If you are having problems, see this article:

http://support.microsoft.com/kb/q193011/

There is a link on that page for additional help also.

I had high speed internet for two years with Win98 and got excellent speed from it.