Lousy Performance, High Hardware Interrupt Usage

My system has been dog doo slow since I did a reinstall a couple weeks back.  Process Explorer was showing some outrageous hardware interrupt rates, on occasion as high as 50% and regularly at 20%.
I’d let it roll for a couple weeks simply because it was low on my frustration list and I was trying to roll through other things.  It finally pissed me off enough tonight that I spent some time nailing it down.  Turns out ATA/IDE controllers will often revert back to PIO mode instead of Ultra-DMA.  (MS KB article on the problem here.)
Check the problem by examining the controller’s Primary and Secondary IDE settings: Device Manager -> IDE ATA/ATAPI controllers -> Primary or Secondary IDE Channel -> Properties -> Advanced Settings.  Look at the Current Transfer Mode field.  If it’s “PIO” then it’s a FUBAR PITA and you’ll need to uninstall the driver, reboot and let XP do its magic reinstall. 
Sucky, but fixable.  Now I’ve got my shiny system back shiny again.
Now Playing: Olu Dara — In The World: From Natchez to New York.  Wow, jazzy/bluesy/folksy goodness.  Amazing clarity, terrific vocals, killer guitar and harmonies.