upgrading PHP

I'm interested in upgrading the PHP on my RedHat 7.1 server from 4.04 to 4.1.2. If anyone has any experience with this, I would like to know the following...

- Did the upgrade cause any side affects? Did your scripts stop working, or did they start act strangely? Did your hair fall out? Did you suffer dizzy spells?

- Can I undo the upgrade if things don't work after it's finished?

- How long does the upgrade take? Minutes? Hours?

- Is there a place where I can get detailed instructions on performing the upgrade?

I'm a bit afraid, err, well actually I'm terrified. If anyone could shed some light on this, it would be greatly appreciated. Thanks.

 

 

 

 

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