All that is left is to code the JavaScript for the mouseovers. I use a preload script so there is no wait when mousing over. Optimally, you would use a splash screen and redirect that preloads the images for your nav bar so it they are already loaded when the viewer gets to the page with the nav bar on it. When using nav bars for your site, you want to use just one through the whole site. You can use it on all the pages, but don't get crazy and make a different nav bar for each page.
Nav bars are image heavy and slow load time.
If you use just one, everything is preloaded and ready for each page, unless of course your nav bar images have really large file sizes. The trick is to create a nav bar that you can keep the file sizes as small as possible. If you have questions, feel free to email me .