First off you don't need to do anything with the bios editor.
You can do overclocking in software and as for the fast writes and side band addressing if their turned off in the video card it's usually for a reason.
Rivatuner and the Coolbits reg can tweak all of the above.
I highly recommend reading the docs that come with rivatuner as it will explain what to do.
To reveal the nvidia panel create a new text file and open it in notepad and copy and paste this into it:
Windows Registry Editor Version 5.00
Save and close notepad and rename the text file coolbits+.reg right click of the file after the icon changes and select merge.
If you go into the Nvida driver control panel you should now have an overclocking tab and an AGP settings tab. Pretty much everything else is self explanitory after that.