You might be better off getting out at Metro Latina for the Rastro. The market is down the hill from the station - follow the crowds on Sunday AM. Check out www.gomadrid.com for some great maps of the city.
Loc: Washington, DC
cool, I'm sure that either one of the stations will do. I'll be in Madrid from April 7-15, so I will be sure to check out El Rastro. What other activities, that you may know of are going on during Easter Week in Madrid?