pgss2k

So I was under my car this weekend doing some prep for the upcoming season and noticed some play in my passenger side halfshaft. It moves in and out from the diff to the knuckle 1/8 to 1/4" or so with a definite "clunk" when it bottoms out. Is this a worn out CV joint or a problem in the knuckle itself? The car is only used for track days and is on its original equipment but still has pretty low miles. It is used pretty aggressively at events so I have no illusions that I might have worn something out. I have about 3 weeks to get ready for my first outing so I am trying to figure the best thing to do. The fun of tracking is forcing me to learn to wrench some so I appreciate any suggestions. I have some new hubs going on soon but should I be thinking about swapping the halfshaft at the same time?
Thanks
Paul