I had the CPU spiking problem as well. Here's what I learned and how I resolved it: I added a second hard drive and a controller card to my system. I accidentally attached my second hard drive to the first slot of my controller card. My first hard drive (with my XP installation on it) was attached to IDE1 on the motherboard. I have a dual boot system (XP and Ubuntu) and when I installed the grub bootloader onto my first hard drive, so it could 'see' my Ubuntu installation I had brought over from a previous computer, my system wouldn't boot at all after a reboot and I was forced to boot an Ubuntu LiveCD to troubleshoot. I won't bore you with all the details, but for whatever reason, my BIOS was seeing my first hard drive (with XP and the bootloader) as the second hard drive and my second hard drive as the first. So I unplugged my first hard drive from the IDE1 of my motherboard, plugged it into the first slot of my controller card, moved the second hard drive to the second slot, tweaked my BIOS and I was good to go. Then the CPU spiking started. I noticed because my audio kept studdering and had tons of jitter, so I thought at first that I was having issues with my sound card. Again, I won't bore you with all the details, but I made the audio problem, and more importantly, the CPU spiking disappear by simply plugging my first hard drive back into IDE1 of my mobo, and keeping my second hard drive on the second slot of my controller card, instead of in the first slot, which I had mistakenly done when I first added it. Bottom Line: In my case at least, the CPU spiking was caused by the PCI bus being overwhelmed with too many devices sending too many hardware interrupts to the kernel. (I should mention that in spite of this supposedly flawed configuration, I had absolutely no CPU spiking or audio problems under Ubuntu....only XP...I'll let you draw your own conclusions!) So if you have this problem, you should probably be looking into how much stuff you have plugged into your PCI slots and troubleshoot from that perspective. Hope this saves someone some hair pulling frustration!