I doubt if you are going to find any "modded" BIOS files for that board but I wish you luck in your search. However, if you want to "tune it up" a bit, why not just increase the FSB a bit? Does your current BIOS allow for that? If you are running a Duron CPU, (100 MHz), why not try to slowly increase it to see how far you can take things. Keep in mind that you'd better have decent cooling solutions (case ventilation and good HSF) to do this. Also make sure you back up all your critical data because overclocking can lead to system corruption if things get pushed too far. Not trying to scare you away from it but just want you to consider it before you start. Most of us do a bit of overclocking and some take it to extremes but you must be prepared for the downside if things go wrong. Take it slow and easy; step by step. BTW, if your MB doesn't have the ability to change the multiplier right now, it is very doubtful that a new or modded BIOS is going to change that. Sorry.
BTW, Welcome to AT!!

Your first post!