For some of the great modding tools around here it is helpfull to have photoshop; @ the adobe website you can download the CS2 version for free! I know that this is not the newest, BUT it should be fine for most stuff of "game-modding";
Anyway; here's the link:
I uploaded the .dds plugin for you here:
That helps you save time 'cause most pages on the web that offers this are fake or you need to do some stupid survey; ;)
Well, that's it;
Hope that's helpfull for some out there!