How do I know if my system is using the ATA 100 features
of my hard drive and motherboard? I know my drive and
board support it, but when I look in device manager at
the hard drive, it doesn't say anything about it.

You can chk in the BIOS,or if you have intel components,download the
application accelerator from intel,in that you can even set the options on desktop.

Hi;
For XP...
Check under "IDE ATA/ATAPI controlers" and expand.

Mikey