Php and Sql Upgrade compatability question.

I am running vBulletin 3.6.x, Photopost, Reviewpost, vBALinks and vBCEO on my site. It is a dedicated server BTW.

Would I be okay upgrading to php 5.x and sql 5.x? I could really do with the performance boost these give, but obviously I want to make sure everything will work ok. Also, which versions are recommended to be run? (i.e. stable and fast)

Many thanks

[Hornstar]

I'm in the same situation as you. So far I have upgraded to the latest most stable but I am thinking if version 5 is stable, then that would be better. Last I heard it was not compatible with everything.