Joe.
The "cut down" Linux distributions such as Puppy or DSL ought to work on your low spec computers. That is part of the purpose of them.
What you cannot expect to find is all the whistles and bells which can run on newer higher powered computers.
If you have the means to back up the old computer, and to reinstall the original Win98 set-up from scratch - I would give the low-spec Linux a try, and if they do not suit what you need, you can reinstall your previous Widows.
What have you to lose? As long as actual documents are saved off the computer, you can't lose anything you really need.
If you bought new computers with Vista on them and new versions of Microsoft Word and the like, they probably wouldn't open any of your earlier Microsoft documents anyway. You could get better compatability using Linux
Quack!
Geoff.