PHP-eSeller and PHP-KeyCodes can both be installed on a Windows Web Server which runs PHP and has a mySQL database. This is quite a common arrangement now, and many hosting companies provide this, enabling PHP applications to be installed on Windows Web Servers.
Both of the applications work fine on Windows servers and normally work straight out of the box installation.
The only possible issue is sending emails. Both applications need to send out emails from the server and this can be done by configuring PHP-eSeller and PHP-KeyCodes to use SMTP if the standard PHP email has not been set up. This requires minor configuration changes to the config file which means entering the SMTP host, username, password. All of these details should be available from your web site host if you donot know them.
You do not have to use the web server SMTP details, you can use an external SMTP mail service such as http://www.authsmtp.com. Sometimes, these provide a better mail service than your host and may be more reliable.