Does 1.3.8a play well with php5?

I have a cart with loads of modification; having invested huge amounts of time and more than a little cash. I have someone tweaking a critical point and they're asking for me to have my server upgraded to php5. I'm worried about losing functionality or outright breaking the store. The tweaking is happening on a parallel installation for testing but the server upgrade will affect the live store. Any thoughts?

If the upgrade is to php5.2.x then your install should work just fine.

In case the new version is php5.3 you will need to apply a patch for 1.3.8a (don't know the link to the patch, you will need to search the forums)

Found the links:

https://www.zen-cart.com/tutorials/index.php?article=6

http://www.zen-cart.com/forum/showthread.php?t=140960

MUCH MORE IMPORTANTLY, you should be upgrading to benefit from the many additional important security fixes and improvements in v1.3.9

frank- Thank you VERY much for taking the time to find these!
Dr B- Yes, of course, but it's a bit like going to the dentist. Was kinda hoping 2 would be coming out soon. I'm sure it's a lot of hard work and mostly thankless, though, so I understand the delays.

Don't wait for v2. The security protections are much more important.