FINALLY got it together to move from Win98SE to XP. Loaded it onto the PC (which NEVER had a freezing problem before this), scanned for bugs/spyware/malware, no problems.
If you monitor the Task Monitor and watch CPU USAGE, it goes to 100% every 6 'cycles' (vertical lines) or so, then comes down to around 20% for a while then 6 cycles later, does it again.
It doesn't do it all the time. It usually starts after I've been on the computer a while (>30min), and seems to reset after a shutdown/reboot.
This freezes me out for 30-60 seconds at a time, so it makes the PC almost unusable.
What can you wizards recommend?