I had exactly the same problem with my dell installing with the same bios.
The good news is that if you persist, you will get it to a level where upgrades to 10.5.7 and 10.5.8 will resolve any issues.
The trick I used to get the install to 'almost' was to do an "archive and install", then an "erase and install". It got down to about a minute to go before crashing. At this point, I rebooted, and it allowed me to choose the mini's hard drive to boot from and osx started without too much problems.
Either way, keep toiling away, and eventually you will get it down to less than 4 minutes remaining, and you will be able to boot directly into 10.5. Once you have gotten to this point, follow the steps as per the "Fool Proof Install Guide for a 100% Working Macbook Mini 10v!" guide. If you are after more info on my problems, look at the comments on page 7 of the 'chat'/'forum notes'.
(And yes, it appears that it is a problem with the bios - you can either try and fix this (Which was beyond me!), or keep persisting with the install of 10.5).
Hope this helps!