Kurtismonger 0 Junior Poster in Training

I am looking for a utility to track and log a computer's vitals over time for later review, preferably free
My friend has a T60 Thinkpad that I recently replaced the HDD in. It's a fresh install of XP Pro, with all the latest drivers and 3GB of RAM. I've rebuilt dozens of machines and never had a problem. When I use it, it runs plenty fast no matter what I throw at it. He continues to complain that over time it slows to a halt when using Firefox and in general acts slower over time in all programs. It's not just Firefox as I have had him switch between that and Chrome.
Looking for some sort of profiling tool where I can go back and review what he was running and what the vitals were doing.