The latest release of Solaris Express Developer Edition (SXDE) 1/08 is out (here) and I'm running the upgrade right now on my laptop. Last night I downloaded the ISO image (3.7GB - it took 5 hours) using the Sun Download Manager, and today I burned the ISO onto DVD.
So far so good. These things get easier and easier to do with each release.
Stay tuned.
Update: Success !! It took about 1 1/2 hours. No problems. We're now on SXDE 1/08.
