I have already installed a Maxtor Diamond Max 60 Ultra ATA 66 46.1 GB 5400rpm. What does all this stuff mean? can i purchase a Western Digital 40GB Caviar 7200RPM and make it work with my computer? which one is better? im going to set up one for myself with windows 2000 professional and one for the kids with windows millenium edition seperated with a hardrive selector.

Yes it will work with your computer. The faster a drive spins, the faster it can transfer data. The Western Digital 7200 RPM drive should theoretically be faster because of the increased rotational speed. Originally, the IDE interface that these drives are was ATA 33. Then ATA 66 was introduced which has a higher burst data transfer rate and now ATA 100 is around. The Western Digital Drive may be ATA 100 capable but if your motherboard has only an ATA 33 or 66 controller, you will not see the added speed. Any ATA 100 or 66 drive is downward compatible. So, the Western Digital is a faster drive but depending on your machine, you probably won't see much difference. They can both be installed on the same machine as long as you have the master/slave jumper on each set correctly.

Thank you for the quick response. Will i be able to determine whether or not the 100 is only working at 66 somehow becuase of my systems limitations? Will using the two together cause some kind of parity problem. I know that if i use 100mhz dimm with 133mhz the 133 will only preform at 100mhz. is this the same with hardrives?

They will definitely work together. Most probably (and I am not 100% sure) if you put both drives on the same IDE channel, and you have an ATA 100 controller, the faster drive will only go as fast as the slower drive. You will still get the added benefit of the 7200 RPM but not the ATA 100. Most motherboards are only ATA 33. Some boards started coming out with ATA 66 and only recently ATA 100 started becoming commonplace. If your controller is ATA 66 or 100 you will see it in device manager. Also, if you have an ATA 66 or 100 controller, you would have had to install special drivers for it when Windows was installed. Do you know what motherboard you have? I wouldn't worry. Both drives will work together and you will most probably never notice the difference between ATA 33 & ATA 100.

thank you.