Explorer Checker

[PHPGuru_2700]

Hi people!
I have a problem, in netscape navigator for some reason the table is slightly shorter then in IE6 or 5 ( I hate netscape ), I would like to fix this problem by using some sort of Explorer checker, theres most likely a function of some sort, something
like this.

if($_EXPLORER == "Netscape")
{
  $table_width = 400;
}
else
{
  $table_width = 395;
}

[thna_brianb]

$_SERVER['HTTP_USER_AGENT']

OR

$agent = get_browser ();
if ( $agent->browser == "Netscape" ) {
$foo
}