er... be careful doing that, Guido - if there's more than one select box on the page (Like... a language dropdown?), that could end up giving some very bad responses.
Lets make sure we get the -specific- box we're after.
Something a bit more like...
preg_match_all('%<select id="provide_vrm:prVRMfrag:prVRMCon:vrmRegistered".*?(<option.*? value="([^"]+)">.+?</option>)+</select>%', $yourdata, $matches, PREG_PATTERN_ORDER);
(Note: This will change the location of your desired values in the $matches array, because we added another subpattern)