It's a daunting task to wander through the maze of data/video projectors and pick one you think will make everyone in your office happy about using it. Our office uses InFocus, Hitatchi, and Dell projectors. They range from $1,000-$5,000 in price. The most expensive are the brightest and are not considered portable since they are designed for large rooms and not many people would want to carry them around. The InFocus models are our most portable and they have served us well for over 6 years. The typical portable projector burns at 2000 ANSI lumens with a max resolution of 1024x768 and the lamp has a 2,000 hour life expectancy. Those specs are still typical of most portable (under 7 lbs) projectors. If you are shopping for a portable projector, here are some models to consider: Dell 2400MP is very popular. $1100. I see them at conferences and UCD all the time. The resolution and lamp life is the same as most but it has 3,000 lumens (is 50% bthan most). If it is within 16' of the screen, it will be bright enough to leave the lights on in the room. http://projectorcentral.com/Dell-2400MP.htm 5.5 lbs. (Lamp replacement $329) I have one caution for those making the selection without expert advice. Sometimes you'll find what seems like the perfect projector but in reality the lens may require the projector to be 20 feet from the screen because it is designed for very large rooms or even projection booths in auditoriums. Keep an eye on "throw distance". You want the minimum to be within 7 feet (projector to screen). For each projector listed at the ProjectorCentral.com website, there is a distance calculator which I find very helpful. . Mike Poe, Media Services Manager, ANR Communication Services Dell 5100MP
Dell replacement lamp
With portability comes trade-offs, usually in brightness (lumens) and image size. Nearly all portable projectors only have the same 2,000 hour lamp life so no matter what you buy, you'll need to replace the lamp in a few years (depending on usage, of course). And they are not cheap! They typically cost between $300 and $500 to replace and it is not likely that will change in the foreseeable future. Most last 2-3,000 hours and some for the latest models are made to last closer to 5,000 hours, but those are neither portable, nor cheap.
The InFocus IN36 is very similar to the Dell and costs around $1400. 5.2 lbs (Lamp replacement $500)
http://projectorcentral.com/InFocus-Work_Big_IN36.htm I
InFocus IN10 is brand new (Summer 07). $1250. It only weighs 2.4 lbs. The brightness is actually less than most at 1800 lumens, but the lamp lasts 4,000 hours. That's the trade-off, longer lamp life=not as bright. It is small and would work best in small group settings.
http://projectorcentral.com/InFocus-IN10.htm (too new for replacement lamp info.)
InFocus IN42 model. $4,000. Not so portable, but if you really want a bright one, there are projectors with 3500 and 4000 lumens. They weigh 13 lbs and 16 lbs respectively. I wouldn't want to travel much with those since it would require another rolling suitcase to get them around. It's not so bad for a car trip, but I wouldn't want to bother with it at the airport. Also, the lamp life is the same 2,000 hours and because of the brightness, will cost at the high end to replace ($500 ).
At ProjectorCentral.com there is a Buyer's Guide to help you understand the specs: http://projectorcentral.com/buyers_guide.cfm Once you know what you are technically looking for, you can search by feature http://projectorcentral.com/projectors.cfm 
