The latest version of the SDK (standard edition) is 1.5.0, update 6, which you could download from here:
http://java.sun.com/j2se/1.5.0/download.jsp It was cofusing for me, the first time around, because there's SE, EE, ME, with, or without netbeans, etc. etc. etc.! (for the record, SE is, obviously, "standard edition", EE is "enterprise edition", ME is (I think) "micro edition"... whatever ME means, it's for embeded devices, such as telephones, & PDAs, if I'm not mistaken.