Based on the requirements you've listed, it's hard to recommend a direction, other than stating you need a projector with VGA input for the PC, component input for the DVD, and depending on the console, S-Video or component input for console gaming.
Keep in mind that regardless of technology, the performance of the onbaoard de-interlacer important for DVDs unless you have a progressive scan DVD player. Not all presentation projectors have good de-interlacers.
Since you will be hooking up a PC, I recommend a projector with at least XGA (1024x768) resolution. A projector with this resolution will have to scale up DVD and TV signals, so the performance of the projector's scaler is important. Again, not all presentation projectors have good scalers.
Beyond that, the big issues of brightness, noise of fans, DLP vs. LCD, contrast, bulb life, etc. are not able to be addressed without more details about where and when the projector will be used, and your sensitivity to DLP rainbows or dislike of LCD screendoor effect.
If any of the terms mentioned are unknown to you, do a search in this or the *other* digital projector forum on those terms.
An LCD projector in that price range I highly recommend is the Panasonic 711XU, the projector I recently purchased for mainly DVD viewing in mixed lighting conditions.