Here is a guide about recapping your Atari 800 computer!

Capacitor List from Console5.com:
Power Supply, REV B			
C202	470uF	16v
C201	470uF	16v
C211	10uF	16v
C210	10uF	16v
C204	2200uF	16v
C205	2200uF	16v
C207	4700uF	25v
C208	4700uF	25v
			
Main PCB
C179	10uF	16v
C199	10uF	16v

You can order a recapping kit from Console5.com. They also have a Wiki page which lists the capacitor values here.