<b>What is an ATA controller for example a ATA, ATA/100 or ULTRA ATA?</b>
<font color=blue><b><A HREF="http://www.techweb.com/encyclopedia/" target="_new">Tech Encyclopedia</font color=blue></A></b>.
<b>What do these do and would it be recomended that i get one if is was buying a YAHAMA 16x/10x/40x burner?</b>
Yes, ATA100 is backward compatible.
<b>Would it help the speed of my computer if i had my hard drive hooked up to one?</b>
In my experience, I see increasing performance (~5%)when I hooked up my IBM Deskstar ATA66 into ATA100 controller.
Good or Bad have no meaning at all, depends on what your point of view is.