Well I know this is a old thread, but rather than start another I will continue this one...
I am a avid used of Ccleaner on my Windows 7 & XP systems. I have not yet tried it on one of my older systems (2000, '98, '95) These machines are not used for internet purposes either by the way. They are used to support older hardware/software platforms with which I still do tech work from time to time. Anywhoo, after googling this subject and landing on this thread I decided to try that 'oldest' version of Ccleaner 1.16 on my old Compaq contura 400 laptop with Windows '95b. It installed, loaded and executed flawlessly. I've attached a screen shot of the results. It does appear to be doing its job.
P.S. There ARE good reasons to use older platforms and operatings systems...everyone has their own needs. Just be aware of limitations and concerns applicable to your situation. No one can tell you which is best to utilize, only recommendations. Utimately, its up to you to decide.