Question : How should I check whether IIS is installed or not?
Answer :To verify if IIS is installed, go to your 'Add or Remove Programs' utility in the Control panel and click on the 'Add/Remove Windows Components' in the side menu.
On XP Pro and below, you should see an item called "Internet Information Services (IIS)". If this is checked, IIS should be installed. On Win2K3, you'll see "Application Server". If this is checked, select it and then click 'Details'. Another form should open which will contain "Internet Information Services (IIS)". If it is checked, IIS should be installed.