Firstly, if you aren't sure about your RAM, I will assume you haven't added at other than the orinial provided with it.
For a BIOS update, you will need to visit the maufacturer's website and enter your machine type and model number to get a list of the latest drivers.
At this point just look for the BIOS update. It is a small program that you can save to a floppy (A:)disk, when you boot the computer it will read tyhe floppy first and then automatically start the BIOS FLASH (update for the BIOS). Just follow the instructions on screen, VERY simple and it should update to the latest version.
Formet the hard drive (if just one drive labeled C:) then you only need to reformat the C: drive.
Once it is completely reformatted, you can reinstall Windows2K.
BEFORE reinstalling Windows, make sure you haven't got any EXTRA Video, or Sound cards installed that didn't come with the PC (upgrade cards if you have added any).
Once a clean install of Win2K is in you should be able ot reinstall/update the sound and video drivers (ifnot aftermarket that you've added) stright from the Compaq Support and Drivers website.
Find your drivers and BIOS upddate by entering your machine info here:
http://welcome.hp.com/country/ca/en/support.html