Some sites have a lot of good information, but they need to be easy to navigate or you risk wasting too much time getting around in a site. Look for consistent navigation tools. The students will find other things to occupy their time with. If your connection is a problem, there are ways around this. See the comment below.
Computers lend themselves to publishing.
Students can publish or print out materials that have been word processed or drawn. Try to construct lessons and pick sites that lend themselves to some form of outcome. If you have a T-1 coming into your lab, you are probably okay unless the site is iffy. An even easier way is to set up a proxy server that caches a copy of a web site so that other students that use it get it from the locally cached copy rather than having to go out to the Internet to get copies of all the pictures and pages. It should be possible to verify facts within a good web site.