Have you checked out w3c's browser stats? This is VERY helpful when needing to test and/or convince a client other browsers besides IE 7 need to be tested!
If you are guilty of just testing for IE 7, shame on you!
A paltry 20.1% July 2007!! Check out the link below for full stats:
If anyone has any questions or wants to brainstorm about SEO, please post and I'd be happy to entertain your questions. I am an Internet marketing guy by trade and I will be moderating this portion of the udm4 forum!