Note that some of the answers above mention a product called Microsoft Front Page.
This product is no longer available and has been replaced by a product called Microsoft Expression web.
If you are going to design a site DONT use Front Page.
Here is the site for Expression web
http://www.microsoft.com/expression/products/o verview.aspx?key=web
Note Expression is just one product you can use to design a web site, there are loads of others.
Generally Dreamweaver is considered the best but may be a bit complex if you just want a simple site.