While this thread is generating a consensus of 'Yeah, pistols rock', I'd advise the OP to take a look at the join dates and post counts of the majority of the repliers. Using a pistol against AEG's is very doable, but takes alot of skill and experience. I would highly recommend against any newcomer to the sport trying this, as they would likely come away with a negative experience. For the newcomer, a pistol is good for emergency backup and the occasional pistols only battle, but little else.
Think about it: A pistol usually firing a couple of rounds a second at 320ish fps from a six inch barrel, with a 25 round mag and iron sights. Versus a full auto AEG firing 10 to 30 rounds a second at 350-400 fps from a foot and a half barrel, with an 80 round mag, optics and a shoulder stock. Without a lot of skill on the side of the pistol wielder, who do you think will win the majority of the time?
Pistols do indeed rock, I love my KJW 1911 to pieces. But I wouldn't use it in battle against an AEG unless my M4 was bone dry of ammo. And in that instance, I wouldn't have high hopes of winning. If you want to go light-weight in battle, think about a good subgun like a p90 or mp5k-pdw rather then pistols.