Quantify whether you have the ability to do a rear projection system. Rear projection is definitely the best for "Home Theater" if you have the room.

If you can do a rear projection system anything above 2000 lumens will work. Provided the space behind the projector is enclosed and ambient light can be controlled in that enclosure.

You can do rear projection in a space as small as 5' from the screen for a home theater set-up. In that set up the project is pointed at a mirror which bounces and expands the picture to the right size.

What to look for in a projector: (please note that these specs are minimums)

Minimum Lumens: Rear projection (2000)
Front projection (4500)

Contrast Ratio: >1000

Bulb: Arch type Bulb (not filament)

Minimum Bulb life: 2000 hours

Aspect Ratio: Both 4:3 and 16:9 (widescreen)

Resolution: 1280 x 720 (HD) other wise know as 720p (progressive)
1920 x 1080 other wise know as 1080i (interlaced) or 1080p (progressive)

If you can, try to find a projector that has sealed optics.

Panasonic has some new models that are liquid cooled (so these baby's are really quiet) and have sealed optics.
PT-D5500U
PT-DW7000U
PT-DW7700U