There are a couple of problems that you may run into. While bandwidth wouldn't normally be a problem, if your wireless association from AP to client is poor then your pings could show it, perhaps significantly. Interference or a noisy environment cause poor signal quality or signal to noise ratio. This could force the wireless client and/or AP to drop packets. The other thing you might run into is if your running XP, MS zero wireless configuration utility has been known to cause hiccups.
So...as long as your AP to client association is solid, ie. low SNR, and XP isn't causing you any problems, you wouldn't see any difference whatsoever in a wireless client device vs a wired one. The wireless hop from client to AP might add 1-3 ms under optimal conditions. Adding more wireless nodes to the AP might introduce some latency depending on the load. AP's are akin to wireless hubs, using Collision Avoidance vs Collision Detection being the primary difference besides the obvious medium difference, microwaves vs copper. There is no yes or no answer to this question until you test and setup your WLAN.