I dont think that u need to download gd2 from boutell. I have done that too, actually and finally found out that php that I downloaded from php.net in zip format has already included gd!
So, you just need to edit php.ini and remove the ";" sign from the gd2.dll. If you are not sure what I am talking about, just open your php.ini and check it by yourself.
Review your php installation by using phpinfo() function.