How can I see which processes on Windows XP are accessing the file system?

Question

Some process on my XP workstation is randomly clobbering performance for minutes or hours at a time with, I believe, a steady stream of hard drive access.

This does not seem to correlate to processes with heavy CPU usage, so is there a utility I can leave open that will show which processes are hitting the file system the most?

I don't know if the situation is reads, writes, or just checking metadata of files and folders.

This is a corporate laptop running up-to-date AV software, so it's far more likely to be the AV software than malware. Unfortunately, IT department has no answers, so I'm on my own here.

Answer 1

Process Monitor (formerly filemon & regmon) should do the trick for you.

Answer 2

Process monitor(direct link) from Sysinternals does exactly what you are looking for.