"BTW, one is a 160gb Seagate that came out of my DirectTV DVR."
That had linux on it so you have yet to rewrite the MBR. I'm going to decline writing how to format a drive or write the MBR since you can find that widely on the internet.
To keep your machine from booting that drive don't put it on your PRIMARY IDE connection. Use the Secondary next time.
Excuse me if I ramble a bit but I have several problems. First the system I am working on is a homemade system that I built several years ago and have made several updates too. My current problem is with several HD's I have that I would like to clean, reformat and use in a couple other systems. I really and looking for a simple way to plug the drive in as a Primary Slave and then FDISK it. This is proving harder than I thought, if I set the drive to cable select, my system attempts to boot from them and I get a screen full of 01 01 01 01 01 01 or a screen with 04 04 04 04 04 04 I finally got one drive reformatted using the Computer Management tools, then I downloaded a set of utilities called "Ultimate Boot Disk", somehow while using them I have messed up my Primary Master drive which now shows to be only 32 meg and the 110gb drive I just got reformatted shows to be like 667GB. I am really ready to just dump them all and wipe them clean, and reformat these drives. Is there an easy way to wipe these drives clean? Clean the partitions? Check there integrity? and reformat them? BTW, one is a 160gb Seagate that came out of my DirectTV DVR.