Emergency Upgrade!

One of my clients' servers got hacked and he went for a complete Linux upgrade and now his ZenCart site doesn't work so I need to do the world's quickest upgrade.

He was on v1.3.7 which was working fine and I can't see anything that says it wouldn't work on later versions of Linux, which is usually fairly backwards compatible.
Can anyone point me in the direction of anything that says what the MAXIMUM versions of linux, PHP and MySQL should be for 1.3.7? Otherwise I'm going to have to go to 1.3.9 and it's not going to be pretty!

update - apparently the new server has PHP 5.3 on it.

I can't see any reason why zc 1.3.7 should fail - what am I missing?

For php3, zencart versions 1.38 and below require Patch
i.e.
http://www.zen-cart.com/forum/showthread.php?t=140960

And you should think about gong to 1.3.9 anyway. Otherwise you're almost inviting hackers to try again, and don't have adequate defenses.