Utilities Tools Win-98SE

Please Need good advice.

I install Win-2000 as a separate OS my primary Os is Win-98 SE . However, when I tried to run my Scandisk and Defragment tools the system operating Win-98 was not running properly it keep skipping from 0% to 1-2% on the C: drive and back to 0%. I ended deleting my Win-2000 and leaving only 98 but, I haven’t been able to fix this bug…
If I install Win-98 again would that delete every thing in my HD ??? Pls, Reply.
Also, I’m planning to overclock my BUS chip(Celeron 66MHZ-64RAM)or should i first upgrade the RAM is this a good idea? recommendation?…thank you.