There won't be much mistletoing or hearts a-glowing among e-commerce sites if they aren't ready for what's supposed to be their most wonderful time of the year.

Most retailers generate 20-40 percent of their annual eCommerce revenues and profits during the holiday season, according to Web research firm CoreMetrics. And contrary to popular belief, the Monday after Thanksgiving isn't the biggest holiday sales day of the year.

Sure, that Monday, often dubbed "Cyber Monday," will see the highest traffic this season. But CoreMetrics predicts that sales on the following Monday, December 4th, will be 19 percent higher than "Cyber Monday."

The number is based in large part on data from last year when sales on the second Monday after Thanksgiving were up to 22 percent higher than those on Cyber Monday.

It's supposed to be a big year. CoreMetrics predicts that the 2006 overall holiday retail sales will increase 16 percent over last year's holiday season.