I wouldn't bother trying to move the default xampp htdocs directory, it will probably cause more problems then it's worth. Instead you should create a virtual host. That way you can specify as many hosts as you want and where you want the files to be on the drive.

I have xampp installed in: C:\xampp

And my vhosts are in: C:\home\hostnam e\public_html

Because on my real server, the linux directory layout...