I cannot believe that there's only been such a small handful of The West Wing mentions in here. Inexcusable. It is clearly the best show of the decade, hands down. It's one of the greatest series ever to grace the small screen. Aaron Sorkin is an unqualified genius in the craft of screenwriting, and the first four seasons of The West Wing are the proof(the last three after Sorkin left are also great, but not as unbelievably great as the first four). Simply brilliant television. Even if you're not all that into politics, it'll win you over anyway. The characters are some of my favorite characters in anything, ever, big screen or small. Season 2 of The West Wing is a candidate for greatest season in TV history, imo.
Also, while not nearly in the realm of The West Wing or many of the other shows mentioned in this thread, I'd like to give a nod to the WB series Everwood that ran from 2002-2006. Solid, solid series, good writing, good acting, great drama.