Well, there good for Paint.
But the thing is that Paint...isnt that good lol. I suggest downloading Gimp, its free, almost like Photoshop, and its awesome. Plus, its totally legit. Its not one of those really unknow, crappy photo manip program that nobodys heard of... alot of people use it.
I like what you've done. =] However, I have one question about the first picture.....
Why would anyone want to use a saw like weapon against zombies??? (what weapon is that???)
If I was having to fight zombies, I'd try my hardest to find a gun. If I didn't have a gun, I'd try to run in a nice open place so I can see everything around me and not get trapped in a corner. I highly doubt that a blade is going to do that much to a zombie unless used properly. Which being in a tense situation like a zombie invasion would most likely not permit anyone to think well enough to use it properly. It's a good thing I'm going to join the Air Force. =] I'll have weapons at my disposal when all this goes down. XD