Even with a 7mbps cable connection it took several minutes to update. Note that I did not delete the *contents* of the dat folder, I deleted the entire folder (including it's contents) as well. Update restored the folder and contents, all with the current date, which seems to satisfy the program so as to not generate error messages.
Like I said, even with a cable modem connection, that rotating arrow seemed to go on forever. I finally went and took a shower and when I returned it was finally done.