xampp is probably the cause of your performance issues. Get it off your system!
Then do it this way:
Enable IIS 7.5 on the server and make sure it's tuned and working nicely. Make sure you select the CGI role. That will allow you to install PHP under FastCGI - you want to do that on Windows.
Once IIS is running download the PHP .zip archive from php.net. Extract it and then map the php-cgi.exe file to the .php extension in IIS.
Download and install MySQL and phpMyAdmin. Create a blank database for Moodle. Create a database user.
Run PHPInfo() to confirm that PHP is running properly.
Download the latest Moodle .zip package from download.moodle.org and extract it to a folder on the computer.
Create an application in IIS for Moodle and point it to that Moodle folder. Set the default page to the index.php file in the Moodle folder.
Go to http://yourserver.com. The Moodle installer should be triggered. Follow the instructions to install Moodle.
http://www.bfcnetworks.com/whitepapers/ has some really good whitepapers that explain the process nicely - for MySQL and MSSQL. But they do leave out a few things - like the extensions that you need to enable in your php.ini file (php_intl.dll, php_xsl.dll, php_curl.dll, etc... See http://docs.moodle.org/26/en/PHP#Installing_.28missing.29_extensions)
But before you do ANYTHING, first spend some quality time reading the Moodle installation documentation on http://docs.moodle.org/26/en/Installing_Moodle. It will do you lot of good.
On Windows, learning to install Moodle this way can be more time consuming, but you gain intimate knowledge of the process which means that you'll be better qualified to maintain and support that Moodle installation. If you don't want to do that, then you should probably get somebody who knows how to do it for you - hire a techie or a partner.
