My system is stuttering!!

After bringing my computer back upstairs from testing the wireless connection devices, i reconnected my pc, and now my system doesn't stop stuttering!! mp3's stutter, the mouse doesn't move smoothly, some windows take longer to open than others...this is a 900Mhz system!!! I didn't even think about windown opening speed before now. What a problematic week!! What could be the problem?? Messing with the networking options couldn't have done this, could it? It's like the system freezes up every five seconds for half a second, and then continues running. it's driving me crazy!! help!!