That is a pretty good translation. The strtotime function is powerful, but not extremely fast. You would probably get better performance by using mktime:
// Arguments: hour, minute, second, month, day, year
$datCurrent = mktime(0,0,0,$intMonth,1,$intYear);
$intCurrentMonthDays = date("t", $datCurrent);
$intWeekday = date("w", $datCurrent);