Install 1.5.0_01 on Windows.
Go to Add/Remove Programs.
Under currently installed programs listing shows:
J2SE Development Kit 5.0
J2SE Runtime Environment 5.0

Should be
J2SE Development Kit 1.5.0_01
J2SE Runtime Environment 1.5.0_01

Also if earlier builds for 5.0 are installed, then in the Add/Remove Programs both installations appear with the same name, causing confusion. The only way to make out the difference is the size of the two installations.
           
###@###.### 2004-09-15
###@###.### 2004-09-15