AFAIK Fujitsu laptops are the only ones with a secure BIOS
Caveat: This info was true as of 2005 and is entirely from memory so it may contain some slight inaccuracies regarding the hardware.
I have never encountered a BIOS that could not be bypassed some way or another until a few years ago. Usually there will be a tool/utility/info on one of the more unscrupulous forums dedicated to such tasks (admin backdoor/ password reset or removal/brute forcer/hex editor/jumper short - old skool). However, after a particularly hasty bid on two cheap Fujitsu laptops listed on FleaBay for spares or repair, I found out the hard way that this is not always the case.
You see those clever chaps over in Singapore realised what most have already posted on here: Give someone a scope and enough time and they will prod and poke your BIOS until they find a way in.
So they developed a proprietary daughter chip that sits alongside the BIOS chip. This chip creates a secure communication channel between the user and BIOS using proprietary encryption. The result if you forget your BIOS password? You need to send the laptop board to Singapore to have the password reset by a Fujitsu engineer. Or buy a replacement board yourself for about £100 more and save yourself 6 weeks wait. Suffice to say, the car-puter project didn't warrant that sort of expenditure and one of those two laptops is still available should anyone want a 1ghz Athlon lappy that can only boot from live CD's or HDD (caddy not included).
Further research (at the time) confirmed Fujitsu were the ONLY manufacturer to produce laptops with a secure and unbreakable BIOS password policy (thanks to the daughter chip). It would surprise me not if this were still true today.