Nothing slows down a site better than a 100K wave file. NO 'Under Construction'. It can be taken as fact that all good web sites are under going some change, this is what makes them worth revisiting. If a page is not ready for the NET for everyone to see then don't upload it. If the amount of time finding the best 'under construction' image and placing it on a web page was put into improving the actual content of the page, the whole web would be a better place for it.
Web pages are under constant development.
You would be surprised how different Netscape's Navigator and Microsoft's Explorer can be for starters. What screen size if other than 640x480. Many sites are being designed for 800x600 and that is fine. But at least let people know there is a very good reason why your site looks hopeless at 640x480. It should also be remembered that some Mac users could be looking at the site with a width of only 470.