Most Internet users are well educated. Misspelled words and incorrect usage can make you look like you don't care. Some people have Sparcstations and T1 connections, and some people have Mac classics on 2400 bps modems. You can't predict where your web presentation will end up, so you have to anticipate the limitations of the technology on the other end. Remember that the least common denominator is still text.
Text is fast and can be displayed on anything.
Even someone with a dumb terminal dialed up to some creaky old UNIX box on a 1200 baud modem can use lynx to get content from your web presentation if your pages contain well-written text. So consider making your introductory page mostly textual. If you must have images, then arrange your layout so that initial images are relative small and will display quickly. If you have many images, consider isolating them on their own page or set of pages so that information that can be conveyed with text doesn't have to wait for images to be read. While your SGI graphics workstation with a direct connection to a web server may display images fast enough, the reader with a Windows machine dialed up on a 14.4Kbps modem isn't going to be nearly as happy.