Michael D. Lambert, senior vice president of Dell Computer's enterprise systems group, and Joseph A. Marengi, senior vice president of its Americas relationship group, have filed with the SEC to sell more than $2 million worth of their Dell shares. Marengi has filed to sell 16,142 shares with a value of nearly $969,000, while Lambert has filed to sell 20,274 shares with a value of $1.2 million.