I am presenting a lecture at a class using a powerpoint demonstration. I have not been at this school before, and want to be prepared without having to call the AV department.

What cable do I need to hook up laptop to those overhead projector screens that take laptop hookups? Just a usual USB?

Thanks

The projector usually comes with the cable you need. It hooks up to the laptop's VGA port. It looks like this (the blue one):

http://canisius.edu/images/userImages/mdcweb/Page_3668/Laptop%20Connection%20Pics%20002a.jpg

Cables To Go - 6ft HD15 M/M UXGA Monitor Cable with 3.5mm Audio (http://www.cablestogo.com/product.asp?cat_id=3206&sku=43095)
http://www.cablestogo.com/assets/product_images/43095.jpg
The whole cable looks like this. But any video projector would have this cable already... typically.

I didn't search too hard, but if you're determined to buy one yourself, get a long one... like this one:

ValleySeek: CablesToGo 52061 - 15ft VGA270(TM) HD15 M/M UXGA Monitor Cable (http://www.valleyseek.com/product.action?itemID=6671)

And if you don't need sound:

http://cgi.ebay.com/15-FT-VGA-SVGA-Monitor-Cable-Male-Male-M-M_W0QQitemZ220289834078QQcmdZViewItem

For those (like me) who have MacBooks, you also need a small Mini-DVI to VGA adapter cable (http://store.apple.com/us/product/M9320G/A) to make it work. You also need an adapter with a MacBook Pro, described here (http://store.apple.com/us/product/M9267G/A).