[dba-Tech] Question about Vista RC

I have three computers that one might think the Vista RC would work on, but it works on none of them. 

1. Toshiba Tecra 2GB RAM 2 GZ disk. Message says "cannot install on this box without a BIOS upgrade." The Tosh site is less than useful, in terms of easily finding the BIOS to download.
2. HP duo-core 2GB RAM, purchased only months ago. 64-bit Install hangs -- boots up ok then dies.
3. P4 1.5 GZ 1.5 GB RAM, 32-bit install won't even boot. For some reason this box doesn't even recognize the DVD, although the others do.

Anyone got any ideas?

TIA,
Arthur