Upgrading Drupal

My host is going to upgrade from PHP 4.4.0 to 5.2.0 in a week. Since they are very nice people (non-profit IT-student association) they have copied my sites to a test server with the new config running.

I have a few Drupal 5.2 sites. One of them works fine on the new server unless I try to go to the admin pages -- then I get the dreaded White Screen of Death. The other two sites, which have a lot more modules, show a white screen from the start.

I already upgrade my site from 4.7x to 5.x
I used my old theme i.e bluemarine theme (i.e.custmize theme)
where I created user_register.tpl.php

now this code is not working into my upgrade site.
please any one know solution please give me.
It's very argent.

thank you

I upgrade my site from from drupal 4.7 to 5.1
all are working fine but into new site
new user can't register , site always shown error :

* You must enter a username.
* You must enter an e-mail address.

Already data is entered into textbox
please help me if any one know this.

thank you

I have installed Drupal 5.2 version on my machine.
I am trying to add "helpdesk" model in it.
I have downloaded it from site, unzip it and copy in modules folder.
But in website in administration - > modules section, it is not getting listed.
What do I need to do?
Thank you.

I have searched and searched for general instructions for upgrading modules. Usually the documentation for modules that I want to upgrade don't include instructions for upgrading unless it's a major release, like 4.7 to 5.x.

I need to do upgrades, for example, on a 5.x-beta5 to 5.x-1.6...but I'm afraid of ruining my sites (multisite installation, shared database with some unique table prefixes) !! I'd like some step-by-step instructions...

Does anyone know if these exist? It seems like they would be in the handbook somewhere, but I haven't been able to find them.

I'm running drupal 5.2, and after a site transfer, my site doesn't load. It gives the error:

Warning: require_once(./includes/bootstrap.inc) [function.require-once]: failed to open stream: No such file or directory in C:\HostingSpaces\pyr0t3chnician1\pyr0.commoncritics.com\wwwroot\index.php on line 12

Fatal error: require_once() [function.require]: Failed opening required './includes/bootstrap.inc' (include_path='.;C:\php5\pear') in C:\HostingSpaces\pyr0t3chnician1\pyr0.commoncritics.com\wwwroot\index.php on line 12

Anyone know what that means or how to fix it?