xpacific has good tips - note that the Keisei line also has an express - Ueno Skyliner which is both cheaper and easier to get into.

Of course, if you REALLY are in a hurry - the taxi ride is only about $200...better than missing a flight!

I'd also add that the best ATM period in Tokyo is the one in the Sumitomo building in downtown Shinjuku - the Citibank ones never liked my Bank of America card