Disabling IDE drives in BIOS isn't presented so bluntly. When you go into BIOS, choose the one that says "Standard CMOS Features" or something along those lines. In there you should find four selections that say :
HTML Code:
<pre>
IDE Primary Master auto
IDE Primary Slave auto
IDE Secondary Master auto
IDE Secondary Slave auto
</pre>
one of them is your cd-drive. just highlight it and change the value to disable.
If none of this is in there, sorry for wasting your time.