offline old computer: how to use

Hello
I have been given a a Packard Bell Club 533-C with 64MB RAM that my relative no longer wants. It runs windows 98 second edn. So far I have booted it up and opened up the documents. It is offline and I have no desire to put it online. To me it's a junk computer to experiment with and maybe put Puppy Linux on; my stuff for work is on a different computer andonline with Windows XP/Linux dual booted.

My question: how do I assess the malware state and disk health/total health of the offline computer? I would use Speedfan but that uses online stuff. It is quarantined for now; if I use any disk in it the disk is marked as such. Also, if I overwrite the whole OS with Linux will that get rid of any malware/viruses?

Also, any suggestions for experiemnts that help me to learn about computers would be good; it doesn't matter a lot of I ruin the computer in the process. It is a junk machine for experiments.

Thank you