Depending on how deep you want to go with that wipe, the best thing to do is use DBAN
. A one time pass will suffice.
Using the Windows "format" method will not do the trick, because there's no actual format. It removes the file location indexes and calls it good. During the install, even without the indexes it will scan the sectors and re-use system files. If the system has a root-kit or something nasty on it, a normal Windows format during install will just put it right back to the way it was... depending on how crafty the malware is, of course.
If by BIOS you simply mean that you're going to do a factory reset, that should be fine. If you're super paranoid then you can just get the BIOS update if there is one available. I don't know of any off the top of my head, but I'm sure there exist tools to re-flash the BIOS back to N version. I should caution you though, flashing a BIOS is dangerous. If it fails, if something interrupts that process... the motherboard is shot without some intense hacks to get that thing back on there, or calling the manufacturer or a specialty shop.
Unless you've been the target of a hardcore government agency, simply nuking the drive and reinstalling windows with a BIOS factory reset should be just fine.
Humans are the only creatures that won't live up to the their potential. Give everything your all. When you die, die on E.
So I ask you, what do you intend to do now?