A pair of white gold cufflinks, a fine Swiss watch, and a set of stainless cutlery will last a century. An HDTV, a laptop, and an iPod will not - which makes knowing when to break out the high-limit American Express and invest in something nice, and when to make a trip to Wal-mart and buy the cheapest box on the shelf, a tricky game. On one hand, everyone would like to own a Dell Adamo, a Sonos music system, and a 50-inch Pioneer Kuro. But then again, most of us would love mansions and Ferraris, too. So unless you're reading from a teak deck on your sailboat in the French Riviera, it might be wise to figure out where to spend and where to save.