i don't have any experience with the i860 sorry
also edit your title to i860 and help will arrive faster
and you can read up at
http://forums.2cpu.com/ on the different boards available.
depending on the factors important to you such as overclocking, ram ddr vs rdram
there is a similar question answered
here that may provide some answers for you or at least give you a better idea of what you want as far as features etc...
hope this helps
mike