High CPU usage

My computer has a pattern of maxing out CPU usage when certain video files are told to run. It does the same thing when the list of some 60 gigs of video files are viewed on the disk through "my computer". What happens is that one drive (maxtor) that has only 40g is usually ok when viewed. But the other disk (Hitachi) with 60 gigs (partitioned in to 100 gig parts) is viewed it sucks up cpu usage for 1 or 2 minutes. This occurs when the scroll bar is moved down more and more to see additional files. No files are being run. I'm only viewing the names, size, details of the files. There are some 150 video files on this drive. The cpu usage maxes out when certain files are played as well and stays upward of 95 to 100% capacity. It typically should be about 40% from experience. I usually have to manually end the process through task manager to get the cpu usage down to 5% again. It's very irritating. I don't think its the hard drive because it did this before and after my hard drive upgrade. I reformatted both drives and reinstalled windows and it still does it. My cpu is new and after installing new memory, 1.5 gigs total, it still does it. My cpu temp on die averages 55c and external cpu temp averages 47c. It will still have the cpu hangups even if fsb is increased from 333 to 400 (increasing Athlon from 1833 to 2.2ghz)

Amd Athlon Xp 2500
Soyo Kt600 Dragon Ultra
1.5g corsair 3200
Hitachi(1 month ata 100)/Maxtor drive (4years old ata ??)

Thanks for the response to my stupid questions. To clarify there are 2 IDE ports.

IDE 1 is a 60gig drive partioned into 4 parts with boot files and windows XP on it. Its the Master 1 with a slave DVD-RW attached to the middle. No problems with speed on this drive. And I believe It's under 100 ata with setting to DMA.

IDE 2 has the Hitachi drive with a total of 200g partitioned into 2 parts. This is the drive that has problems. It is the secondary master with no slave attachment. It is 100 ata and set to DMA.

I've tried reversing the IDE cables so that the ide 1 becomes ide 2 and visa versa. but there are big time cpu hangups with that.