First, you have to install the corresponding security patches from Microsoft. If you don’t do that, you will get soon infected again, no matter how well you remove it.

You can simply delete the file TFTP944. Or, you can try the avast! Virus Cleaner (though there is a lot of RPC-exploit worms, I’m not sure if it will remove exactly this one).

I don’t understand that “because it is in a Windows program file”… what exactly do you mean?