This web site does not support workflows created by SharePoint Designer

Workflows help people to collaborate on documents and to manage project tasks by implementing business processes on documents and items in a Microsoft Office SharePoint Server 2007 site. Workflows help organizations to adhere to consistent business processes, and they also improve organizational efficiency and productivity by managing the tasks and steps involved in business processes. This enables the people who perform these tasks to concentrate on performing the work rather than managing the workflow.

Would like to share some resolution details for the workflow issue that I had resolved recently. here are the details:

Error Message: This web site does not support workflows created by SharePoint Designer

Cause: You do not have the permissions necessary to create workflows.

Resolution:

1) In Office SharePoint Designer 2007, in the Folder List, right-click the Workflows library, and then click Properties.

2) Click the Security tab.

3) Click Manage permissions using the browser.

4) In the browser, on the Permissions: Workflows page, click New, and then click Add Users.

5) Add the user to the list.

If you have any queries/questions regarding the mentioned information then please let me know.

I would be more than HAPPY to HELP you as well as RESOLVES your issues, Thank you

Referrence:
http://office.microsoft.com/en-us/sharepoint-designer-help/create-a-workflow-HA010100591.aspx

http://msdn.microsoft.com/en-us/netframework/aa663328

http://msdn.microsoft.com/en-us/library/aa480215.aspx

http://msdn.microsoft.com/en-us/netframework/dd980559