I found the following message, which appears to be sent by Derick Rethans to an Xdebug mailing list in February, 2008, here.  For those not yet in the know, Derick Rethans is the creator of Xdebug.  So, when he expresses some doubt as to whether Xdebug can work in Vista, especially the 64-bit version, those of us striving for the kind of project demonstrated here should pay careful attention.  The purpose of the demonstration project on this site, of course, is to show that the 64-bit version of Vista does work with WampServer, Eclipse, Xdebug and Drupal Multisites.  It's just a question of setting all of the configuration options correctly.  Thankfully, the default configuration settings are correct in most case.  This website explores the few settings that need careful consideration.

[xdebug-general] Re: php 5.2.5, apache 2.2.8, and xdebug 2.0.2 in windows vista...

On Thu, 21 Feb 2008, Alex wrote: 

> I recently upgraded my local apache install and xdebug dll. When I load 
> phpmyadmin, I get a hard apache crash and vista is saying that xdebug is the 
> module that crashed it. Is there an output that I can generate which would 
> give you more info in order to debug this crash? Has anyone else had this 
> problem? 

Yes, the folks at ActiveState reported something similar. We might think 
it's an incompatibility between MS VC 6's libc and Vista. However, 
linking Xdebug against a new version, also requires you to do the same 
for PHP and Apache. For PHP it can probably be arranged, but Apache is 
trickier. 

(PS: please use the mailinglist) 

regards, 
Derick