Something I inferred from Alan's post is that the main differences between HT projectors (projectors from HT companies) and presentation projectors are features. If Alan is not claiming this, then I am sorry for mis-interpreting.
I think many on this forum would argue that the main difference are not features, but the sales, service, and marketing approach of the manufacturer. I am of that opinion and will use my projector, the Panasonic 711XU,Street value ~3K, to support my opinion.
The 711XU is marketed as a presentation projector, but it has no glaring weaknesses for video presentation. Lets look at some of the specs:
Contrast
Weakest stat by far. Only 400:1. Most DLPs and a few LCDs can easily beat this. Those that are used to CRT projectors, or are very picky videophiles cannot live with LCD contrast, but for those who are looking for a big screen experience, 1000:1 CR and above is not mandatory.
Panel dimensions
The Panasonic is XGA, which is not widescreen, but it has a widescreen mode, as well as an option to view 4x3 material within the 16x9 panel. This is something anyone using this projector on a 16x9 screen or low resolution video signals will love. While you are not using all the pixels you paid for, you are still paying considerably less per pixel than for a Sharp 9000.
Noise:
Low mode is very quiet. More quiet that most DLP HT projectors. Anything above 40 is starting to be a problem for HT use.
Scaler and De-Interlacer
These two functions of a projector are the most important if you are considering just hooking it up to a DVD player. The 711XU's internal scaling and de-interlacing is well regarded and should suit someone on a budget well. Many projectors (some even HT) are regarded as needing an outboard scaler or de-interlacer for a good picture.
Beyond this, in general make sure you match your projector choice to the needs of your room (brightness, distance, mounting options, hookups). If you look for these types of characteristics in a projector you should enjoy it whichever projector you pick.