I DID end up finding a new host over the weekend that used PHP5. After the move was complete my options reappeared and everything has been working good thus far. NextGEN has been a really important plug-in to my site and accomplishes everything I need it to. Didn’t want to give it up!
I spoke to my host (Yahoo Small Business) and they say they’re not set up for PHP5, annoyingly enough. Is there any way I can downgrade my version of NextGen? I’d rather change webhosts (Yahoo is AWFUL!) but that’s not financially possible currently.