I don't practice in WA, but it sounds like you need to hie a local attorney and have them appear for you to resolve the issue. Generally speaking, an attorney should be able to appear without you on a misdemeanor. The DA waiting 9 years to pursue you (even though they probably filed a case 9 years ago) is an issue that needs to be addressed by a pre-trial motion. In California it's called a Serna Motion, it most likely has a different name in WA, but there is certain to be some procedure for this.
Edward J. Blum
Contact a local attorney immediately. It sounds as if, although you didn't have a court date on the case in 2000, that one was set at a later date. Usually, a notice to appear is sent. Clearly, you didn't receive this notification. If this was in California, and the warrant had been in the system for this length of time with no efforts made to serve the warrant, a skilled attorney might be able to have that case dismised.
The sooner you speak with a local attorney who specializes in DUI, the better off you will be.
The first two answer are accurate, however you need to hire a local attorney to show the statute of limitations has passed on the 2000 case and that time has been served. In addition the rules have changed considerable for DUI cases since 2000.
Good luck and don't wait around.