I'm a big fan of replacing old laptop HDDs with an mSATA SSD in a 2.5" 44-pin IDE adapter. The JM20330-based ones have had the best compatibility for me. Just be sure to disable any auto-defrag that old OSes like Windows 98 come with by default :)
Win98 didn't have auto-defrafg. IIRC the first one to ship this was Vista. Win98 still had that atrocious defrag program that would restart every time it noticed that any program modified the file system in any way. So you had to make sure to shut down any program or daemon running in the background. Looking back it's quite amazing you could actually shut down everything that was running and accessing the disk.
I assume the defrag program directly accessed the raw disk and understood FAT, bypassing the kernel, and just used it to get notified about write access to the disk.
