Don't think sp1 is available from MS now. See if you know someone who has the old SP1 CD.
Or just install sp1a, and download and install a java virtual machine. You can access both the MS version and the Sun version from click here
MS is going to continue support for its own version of the virtual machine, which has already been installed by users, until the end of this year (or maybe January next year). Install the 5.00.3805 first, then the 5.00.3810.
Or install the Sun version. It works fine on my w2k sp4. After you install it, you can get rid of the taskbar/system tray icon by going to Control Panel, Java plug-in, Basic tab.