Postgresql vs Mysql

Hello,

I have a simple search engine written for MySQL currently. I am in the
middle of rewriting it
for more speed and functionality, but I am finding MySQL somewhat lacking
(or perhaps it's
my own skill?). The search engine contains from 5000 - 20000 records at any
time. There
are about 5 text (char(255)) fields that need to be searched with simple
boolean operators
of AND, OR, and NOT. This seems to take quite some time currently - up to
60 seconds
on an idle FreeBSD 3.2 server (dual p3 500's, 512mb ram, lvd scsi). If I
rewrite for Postgresql,
can I hope to see any speed increases - or at least equivilant speed?
Under postgres can I
check for a word NOT existing in a set? For example: %rob% <> "Fred Sally
Robert Robin John" ?
(ignoring the case)?

I am looking for general info here - if I should head towards postgres or
not.

Thanks for any help.

Ted