Is anyone aware of a utility that would allow me to manually set the frequency/speed of an AMD Athlon XP-M (Mobile) processor under Windows?

I am using SpeedswitchXP atm, which lets me set fastest/slowest depending on battery/AC/load etc, but since there are a few "steps" in between those fastest/slowest speeds, can I manually set them (or can it be done in Speedswitch?). I am trying to run some older games on my laptop, and running at the full 1800Mhz is uneccessary and only causes the fan to roar like a 747 constantly - the games, being older, run ok at 533Mhz (the slowest) but a little boost wouldn't hurt...

And no, there is no options in the BIOS to do that - it's an eMachines laptop and the BIOS is severely restricted (imo).