I am a very satisfied customer of two Samsung DLP RPTVs, and think you will be very pleased with your choice. I personally prefer DLP over LCD in a rear projection TV. I have not video-auditioned LCOS RPTVs, nor have I compared Samsung to other brands of DLP RPTVs.
Regarding new technologies, Samsung (and others) are coming out with 1080p native resolution sets, and I have heard their picture quality (PQ) is very impressive. However, they are not going to offer 1080p in a 46" size as its questionable if 1080p has any PQ advantages over 720p in a 46" size.
One advantage of Samsung for sure, maybe others, is they will accept a 720p digital input over HDMI/DVI and display the image directly without any additional D/A & A/D or rescaling. This means a synergy with upconverting DVD players for improved PQ.
I recommend getting an extended warranty that includes bulb replacement.
I bought my sets from a local B&M chain that I have done business with off and on over many years. I wanted the peace of mind of a local store, they offered a better price than Circuit City or Best Buy, and I know they provide excellent service.
If instead you want to try an internet purchase, I recommend going to www.avsforum.com and using the TVA Power Buy.