The first colorful iMac, unveiled in 1997, weighed 40 pounds. The dome-shaped follow-up, with its flat-panel screen, weighed 21 pounds. Those computers were cute, but with the new, 18- pound iMac G5, it is tempting to say that Apple has finally gotten it just right. OK, so the G5 doesn't have a built-in Wi-Fi base station or personal video recorder. But its high-tech innards, including the speedy G5 processor, are tucked behind a flat-panel screen and sheathed in the white polycarbonate used on the iPod. Nothing distracts from the screen; even the speakers are on the bottom of the display, pointed downward at your desk, and the on button pops demurely from the back-side. "The computer has gone away," says Apple VP Greg Joswiak. "This allows you to focus on what you want to do." What you want to do, of course, is scratch up the $1,299 to buy one of these beauties.