potential problem with my cavi?

Okay. Just recently ive noticed my engine has had trouble turning over when i turn the ignition. it takes noticibly longer for the engine to start (as if it was in real cold weather or something). But the thing is, is that the weather hasnt been too terribly cold lately, and when it was real cold the engine didnt have this much of a problem. Now, i changed out my alternator a couple of months ago, and had my battery recharged. The only thing i can see is perhaps my battery is going? is there anything else that could be wrong with it, i dont want to go out and buy a battery and find out that thats not the problem.
thanks for the help!

-Daniel D.M.

Test your starter. A bad starter can kill a battery. In the process the battery can become weak and kill your alternator. Good Luck.

how do i go about testing this, and can i do it myself or do i have to take it to a place like autozone.