Rear projection, under ideal conditions, will almost always outperform flat panel LCD and plasma displays.
In bright rooms LCD and plasma do far better, and the ability for plasma/lcd to be wall mounted to truly not add to the footprint of the room is phenomenal.
But, if you can, go to a few good home theater stores and just browse - get up close and personal with the displays.
Time after time, LCD and plasma have processing issues and the inability to produce the same quality of overall image that rear projection can muster.
While rear projection won't be as bright, this simply is a non-issue in a subdued lighting environment, such as this one. As well, it is very common in a basement to have the floorspace to allow for the slightly deeper cabinet.
For the money, I would seriously consider something like this:
http://www.bestbuyplasma.com/Plasma/Product.asp_X_Sku_Y_KDS60A2000
Yes, that's 60" for under $2K.
You can go down to 50", save several hundred bucks, and use the extra cash to get a kick butt universal remote or maybe upgrade some part of your audio system.
Don't forget - audio is half of your setup!