I just set up Apache 2.2.4 on a Windows XP system (from the current .msi), and I thought I'd share my findings about using mapped network drives.
On my old W2K system, I could succesfully Alias to my mapped drives by logging in the Apache service using my account, or a special "apache" account that the IT people had set up for me. But in XP (SP2), it just wouldn't work - the Aliased resource was "not found on the server.". I still don't know why. I tried an older Apache ZIP distro (ABOUT_APACHE.TXT said "February 2002") on the same PC, installing it directly as files and folders, and I had the same problem. I tried the current .msi on a second XP system, with the same disappointing result. If anyone else is trying to deal with this, one workaround is to turn the Apache service off and run httpd.exe in a command-prompt window instead. That worked for me. I've added the httpd.exe to my startup folder.
