I have a hosting account with multiple domains on it, currently running php 4.x. I would like to change this to run php 5.x by default (which the host will let me do) - but will this change anything in the zencart installations that I currently have hosting in this account? Will I need to do an update or change any settings?

I have 3 carts setup - all running zen 1.3.8+

Thanks in advance.