Dell Dimension C521

I was wondering if there was an unlocked BIOS available for this machine, as the one that ships with it is pretty limited. If not, is there any way I could alter the CPUIDs in the stock BIOS so that it thinks my Athlon 64 x2 3800+ is a 4200+? I've already been overclocking this thing using ClockGen and I want to push it further, mainly for laughs.

The latest BIOS can be found here: http://downloads.dell.com/bios/DMC521-010111.EXE