I run a PC shop. Let me know how it goes and if you can't figure it out I can help you. Would be a good idea to know what the motherboard model is and bios type.
Here is a good sheet on how to clear the CMOS and the default bios passwords if its protected.
http://www.wikihow.com/Reset-Your-BIOS
As far as the SATA drive goes.....is the original drive an IDE or SATA?
You probably need to set it to AHCI...of course this depends on how old it is..and you said it was a p4....
It might need some SATA drivers as well for the motherboard....
What OS is this thing running?