This can easily be done is SharePoint Designer. If you have not installed SharePoint designer as a part of Office 2007 Enterprise, I highly recommend it. If you do not have Office 2007 Enterprise edition, MS offers a free 30 day trial of SharePoint Designer to test out as well.

In SharePoint Designer, open the site where you saved the web part page you created. In my case it is located in http://wss. When I created the web part page, I chose to save in Shared Documents. Hit the + and expand the Shared Documents folder to find you Web Part page. Drag the page out of the folder and below the default.aspx page.

This takes it out of the place is SharePoint where is it was stored to prevent other people from making changes. Now it is associated with the site only.

Right click on your web part page and select Set as Home Page

Click OK to the message.

Click OK to the next message if it appears.

To test out all the changes you made, click the Preview in IE button.

Now you can see that your site has the web part page you created earlier, and you are able to edit the page accordingly. SharePoint Designer is incredibly powerful and you can do things much faster here than in SharePoint itself. Try it out for yourself