One of my favorite resources for tracking elections (or perhaps I should say coronations since we are talking about the U.S.... there are few real democratic contests in this country)...but I digress... it's Dave Leip's election tracking/election map site. See here.
You may want to save that to your favorites list. It may come in handy as we get closer to the Primary coronation in a few weeks and the main coronation ceremony in November 2008.
Dave Leip is my #1 tracking site...providing the most updated info all in one site...and in an easy to follow format. The site collects all of the data from the relevant polling services...and provides info over a long period so that you can better determine trends, leans, strength of support, toss-ups, etc. The site also tracks Senate and Gubernatorial races. RealClear politics offers something similar....but I prefer the more streamlined format from the Dave Leip site. Although I do use some of the other tracking sites as well. There are 2 or 3 others that also provide good info.
Be forewarned though- one thing at Dave Leip that might throw you off is that the traditional color assignment for Rep & Dem is inverted. I don't know if they did that for kicks to mess with their readers or what... but after a while you won't notice it.