Last December, over 100 stocks were featured in our Top Picks for 2007 report. Now, at mid-year, we turn to the 20 advisors whose picks showed the strongest gains to get an update on their previous picks, as well as a new favorite stock for the second half of the year.

Ken Kam, editor of Marketscope, chose Valero Energy Corp. (NYSE: VLO) as his top pick for the year; it rose 48%, as of June 1, 2007. Here is his original recommendation for VLO as well as his new favorite stock idea for 2007.

Updating his outlook on Valero, Ken explains, "Refineries were once regarded by Wall Street as nothing more than future hazardous waste sites. For much of the last 30 years, it made sense to keep money-losing refineries operating in order to avoid the cleanup costs of shutting one down.

"Things have changed a lot in the past five years. Today, there is no excess refining capacity and profit margins have soared. The demand for refined products continues to grow along with the economy, but there are virtually no prospects for any new refineries being brought online anytime soon.

"The refineries that were once disregarded are now literally worth more than gold mines. Yet refining companies still trade at single-digit P/E ratios. Valero trades at a P/E less than 7. The S&P 500 by comparison has a P/E of about 16.

Yesterday I spent more than I ever have to fill up my gas tank -- $65!! Based on this report of record gas prices, I know that I am not alone. Are you fed up about this? If so, read on to find out why it's happening and what you can do about it.

I think I was relatively lucky to spend "only" $3.17 a gallon for mid-grade. And I remember spending about $3.25 a gallon after Katrina, so I know that this is not the highest price per gallon that I've ever paid. I just filled up twice -- a little the first time and a lot the second after a long drive. But what really fries my circuits is that I spent $2.11 a gallon in February, a 50% rise in three months!

So what is driving up the price? How can you hedge against higher prices? The answers: 1) demand (gasoline consumption) is growing faster than supply (refining capacity), and 2) consider buying stock in Valero Energy Corp. (NYSE: VLO). Demand is expected to rise -- AAA estimates that 38.3 million will travel 100 miles or more over the Memorial Day holiday, up 1.7% from 2006. And most of those -- 32.1 million -- will be driving on their trip.