When you’re configuring My Sites make sure you put in /Pages/ in the Search Center site settings otherwise it will return you with 404 Not Found error.

For example, if the Search Center site is set to http://moss2010:31000/ then you specify the following:

http://moss2010:31000/Pages/

If it’s set as a sub-site collection, eg http://testsite/sites/SearchCenter then you specify the following:

http://testsite/sites/SearchCenter/Pages/

Hope this helps,

Tommy