what conf to change for php5

[lhwparis]

hi i have installes php5 to another directory on my server to save php4.

what config have i to change to use php5 instead of php4.

i think something to change in httpd.conf but this file is rechanged by plesk. so i think i have to put in something in vhosts.conf ? am i right ?

anything else to to ?
can somebody say me what to put in vhosts.conf to use php5 ?