Well you know, it's not important if 30% of users browsing the web won't have your site displayed properly or anything because you couldn't be bothered to make it cross-browser compatible....
http://www.w3schools.com/browsers/browsers_stats.asp
[rant=BEWARE]
I hate how people just think that because they use or do something a certain way that everyone else will. BE REALISTIC PEOPLE. You're never going to have every single internet user on one browser or even the same set of standards, it's called competition. It's all fine and great that you're just too lazy to put in that little bit of extra code for your images to make them transparent in IE6, but honestly, who are you hurting?
Today, any web design company that isn't cross-browser compatible is really just an oxymoron in itself. The web is a diverse cultural and technological landscape that has billions of users worldwide each with different ideas, beliefs, opinions, software, hardware, and all the rest of it. How can you even represent yourself as a WEB design company if you only cater to a select group of browsers?
Now in the short term, yes it may take you longer to code your layouts and design your sites but in the long term, that's where the gain is for you. You have clients who are happy because their users aren't complaning (why does that image have an ugly grey background that covers up the content?) and the client has a great and functional site that is accessible to everyone (which expands their possible userbase by A TON).
Spend the time now and you won't regret it later. End of story.
[/rant]
Anyways, just had to say that....