Hello,
I'm a newbie and want to use my computer for my karaoke gigs. I've been searching for what I need to connect with my old PA system (rca plugs or 1/4 inch jack or low impedence) I have become very confused over the rush of info I have no knowledge of. Do I need some sort of exterior interface. I'm running a 1 year old LG E500 laptop with vista. I would be very grateful for any advise.
Thanks lariwi

If you're simply trying to connect your laptop's sound output to a PA or external audio amp/speaker setup, you just need to connect your machine's line out to your PA's Line-in.

Alternatively you can plug into your laptop's headphone jack but note that this signal will already have been pre-amp'ed by your laptop-- laptop audio pre-amps are usually crappy and generate more noise than a PA, so you'd want to amplify with your PA.

Anyway, there are cables of all different kinds that you can find at Radioshack or any music store.. 1/4 inch stereo to RCA, 1/4 inch stereo to 1/8 inch, etc., and you can get 1/8 to 1/4 inch adapters as well. Picking which cable you'll need depends on what the line in and line out jacks look like (your laptop's line out / headphone jack is likely 1/8" stereo), but it should be fairly trivial once you figure that out. You basically just need to connect that one cable to your PA and you're done.

If you're still confused, bring your laptop to your local Best Buy or GuitarCenter and ask them what you need to hook it up to a speaker system and they'll probably show you how.