I have to reiterate what Buddha Bart just said. It seems a myth has been created by alot of ppl that disabling the SSID will prevent ppl from "finding" your wireless network. I say dl netstumbler (its free) and run it on your wireless computer. It will pickup your wireless AP with or without SSID.
If you want to make your wireless network as secure as possible, enable WEP (64 or 128bit, if someone wants to crack it, doesn't matter which one you choose), use mac addy filtering (also easily copied by those who want to), and disable DHCP for wireless. Those 3 things combined will keep your novice/average computer user off and away from spying your wireless network. If you want to really secure it, setup VPN or Radius. Both can be done if you have a linux machine and time to spare.
I believe in one simple thing that most computer experts have said, don't use the wireless connection for important things. Define important? Don't check your bank balance or pay bills on your wireless connection (get a wire for those things if you only have a laptop, most laptops have a wired NIC), don't buy things online on wireless. The rest you are up to determine on your own what is important to you or not.
EDIT: You can also prevent ppl from getting on your wireless network by reducing the strength of your signal, so that it doesn't go too far from what you need it for. That isn't an option on my AP.