Solaris x86 vs Linux vs *BSD for PostgreSQL?

Ladies and gents,

I've searched around a bit, and can't seems to find any solid opinion
as to which OS postgresql likes best. Surely some of you, my intrepid
fellow travelers, have done some investigation into this on your own.
What did you find?

I'll be more specific, and describe what I'm using now:

OS: Linux, kernel 2.4.16 with IDE patch
DISK: Linux software raid0 across two ATA100 drives
RAM: 512 MBytes

Total db size is just South of 9 GBytes. Most tables are 50-200 megs,
100-400,000 rows, one big table is >2GB (~4M rows).

I'm not aware of Slowlaris supporting software RAID (at least not
without 3rd party tools) so I'm thinking it's pretty much off the
list. Putting my db on a software RAID0 vs straight disk has
resulted in certain ops going at 10x speed (yes, 10x! (no, it wasn't
due to caching!)).

ISTR that the various BSDs have a concatenated disk driver, which
I'll assume to be not unlike Linux software raid. So, for the sake
of this discussion (unless I'm reeeeeally wrong) let's factor out
BSD vs Linux on the grounds of disk I/O performance.

I guess the thing I'm most curious about is whether there are any
neat little tricks that PostgreSQL uses on BSD that it can't use
under Linux. Any general impressions of which environment it
prefers?

Many thanks.

--Trapper