I have it installed on my 2003 Webserver (live for work) as well as 2 XP machines and 2 Windows 2000 machines. Guess what. Every install had it's own set of quirks and things I had to troubleshoot.
If you are running Sharepoint, I'll assume you don't want that not running which is why I didn't even bring up Apache. In fact I wasn't even aware you could run Apache and IIS simultaneously since obviously they are both going to want port 80. localhost is going to be your default website regardless of what directory it is.
I just assumed default website because typically that's where most people install their websites. Is mydomainname.com for your blog.mydomainname.com not your default website? For example if I wanted to my CEO's blog (which is b2evolution, btw) is http://www.alaron-nuclear.com/presidents-desk/ however, I could just as easily have made it http://blog.alaron-nuclear.com Regardless of how I set that up mydomainname.com i.e. alaron-nuclear.com is my default website and resides in wwwroot
The default website does not have to be wwwroot you could make it any directory you want, but it is going to in most cases be what port 80 is going to resolve to.
I think the thing that confuses me the most is why you get a 404 error when you try to access your database connect test file. What did you do to resolve the 404 error so you could see your phpinfo.php?
As far as wordpress you're welcome to try it. I see that guy has instructions in his blog http://www.iisadmin.co.uk/?p=6 I didn't see those instructions when I tried mine but they look like what I did roughly and in know way did it install as easily as he made it appear. If you do get to the point where you try it and the install screws up like mine did. Save yourself pulling your hair out and check b2evolution.
Sorry I can't help you pinpoint the exact problem, but you've obviously been reading the same things I have, and obviously have done the same things I've done, and obviously know what you are doing.
Honestly, it's why I haven't decided to upgrade my php or MySql versions. It's working just fine as it is, and I don't want to break it lol.
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