|All the 2400+ flavors (8 of 'em) run at 2.0Ghz or less. That said, about the only thing to do is go thru each BIOS screen and look for the option to disable/enable BIOS Cache or Shadow, VideoBIOS Cache or Shadow, etc.|
To echo OtH, those options may not be available and they shouldn't matter anyway.
What is the exact model number and/or product number of your machine? It'll be something like a720n for model and PJ509AA for product numbers. Seems like I also recall that most of this era of hp/compaq came with XP Home installed?