php_calc_found_rows vs count (*)

is it worth upgrading to php 4 for speed?

[ikbenhet1]

Hello,
I'm quering a 30 mb table.
I execute this query 2 times, because i use LIMIT , and i want to know the number of results without the LIMIT.

Is it worth upgrading to mysql 4.0 for beiing able to use mysql_calc_found_rows in stead of querying 2 times? Which one would be faster?
I've read that mysql_calc_found_rows is not (always?) faster then count(row).
Any info about the speed appriciated.

Thanks.

[hakre]

i'm not experienced with mysql 4 that way, so i can't answer, but i'd like to know either. so are there some mysql 4 users with practical experiences out here? ;)