Hey,
today I tried to boot Haiku from an old Laptop: Pentium 3 500Mhz, 256MB RAM (via USB stick).
However it ended in a kernel panic:
http://i.imgur.com/wmW9ACz.jpg
Haiku Version: R1/Alpha 4.1
OK the latest nightly hrev49579 booted.
Running great so far 
Of course it does, with such a powerhouse of a machine… 
Regards,
Humdinger