Some tools linked here to convert between DDS and BMP so you can edit with MS Paint. (Doesn't save Alpha channels though.)
http://www.eqinterface.com/forums/sh...ad.php?t=15368
Gimp is the only free image editor I know if that's worth its salt, but I don't if it supports DDS.
You can also look for free 30-day trials of Paint Shop Pro, Photoshop, etc.