Try the following:

Download the binaries and put them somewhere, for example C:\namecoin\
Press windows+R and type cmd, click ok
now type c:\namecoin\namecoind
It will show the error about the configuration file.
No problem, we wanted it to.
Type cd %appdata%\namecoin
now type notepad bitcoin.conf
It will ask you to create a new file, click ok
put in it the following rows:


Close notepad saving it

Go back to the prompt and type start c:\namecoin\namecoind
This opens a new window that should just show a blinking cursor.
Go back to the previous prompt and type cd c:\namecoin\

To test if it is actually working type namecoind getinfo

Should report the number of blocks, number of connections, and other infos.