Every respectable business presentation these days needs some video or graphic dazzle on a big screen. The portable projectors that allow this magic to happen improve and change almost as fast as computers themselves.

Today's high-end models come close to photorealism. Problems of "ghosting" and jagged lines in the images have been largely conquered. The units do this through liquid crystal display technology that is ahead of what's on the screens of laptop computers. Many have three LCD panels the size of postage stamps that process red, green or blue colors, then combine them to create a realistic image.

You can look for this kind of quality in the next generation of big-screen home entertainment systems. For those who have to lug these things on the road, there's a little bad news. The lightest projector wasn't the best-performing.

The Government Computer News Lab recently tested four units, including playing to several audiences an Apple QuickTime version of the new "Star Wars" movie's trailer. All units performed well, the lab concluded, though some were better than others.

THE PLAYERS

Boxlight Corp.

MP-30T

This one earned the publication's "Reviewer's Choice" designation. It was the heaviest (13.6 pounds), but weight was offset by perfor-mance: the best image, brightness (1,400 lumens) and features.

The unit had superior sound as well. The "Phantom Menace" trailer has whispery background sounds in it; this was the only unit that faithfully played them. The unit's remote control has focusing and telephoto features but was in general harder to use than the other models.

The warranty is for two years. Boxlight will ship you a loaner overnight if you have warranty problems, but it charges for this service.

Price: $7,799.

Report card grade: A-

Mitsubishi

Display Products

X-120

This was the runner-up in overall quality, winning a "Bang for the Buck" rating. But it had slightly inaccurate colors and sound. Whispering segments of the "Star Wars" trailer were missed by the sound system. Brightness rating was 1,000 lumens. Weight was 10 pounds.

Its warranty was by far the best, however. If the unit breaks down within three years of purchase, Mitsubishi will ship you a loaner free of charge.

In terms of price and warranty (but not image quality) this unit was judged the best value.

Price: $5,540*

Report card grade: B+

Epson America

PowerLite 7500C

This unit could use a boost in brightness -- it came in at only 800 lumens -- though it would do well for small to mid-size conference rooms. At less than 10 pounds with a carrying case, it was the lightest of the group.

This unit had the shortest warranty, just one year. For that period, the company will give you a free loaner in the event of a breakdown.

Price: $6,350*

Report card grade: B

NEC Technologies Inc.

MultiSync LT 100

Variable brightness and dull and muted colors were the order of the day with this model. It uses a different technology than the others -- digital light processing, in which tiny mirrors reflect or cancel light. It was in the middle range in brightness, with 1,000 lumens. It weighs in at 10.8 pounds

The LT 100 has a two-year warranty, with free loaners available.

Price: $7,190*

Report card grade: B-

*Internet price