Just got a new receiver with dolby digital ex / pro logic II, dts decoders.
However, i only have 2 front speakers in my setup until i get more. I'm just wondering. can i get anything out of these technologies only w/ 2 front speakers?
No. They are all ways of getting "surround sound". Dolby digital AC-3 and DTS give 5.1 from a 5.1 source, such as DVD: Left, Right, Centre, Left surround, Right surround, the ".1" is the low-frequency effects channel (can be done with an active subwoofer). Prologic and similar tricks use digital signal processing to generate 5.1 from a two-channel (stereo) source.
With two speakers you are better off choosing "Stereo" every time. Some DVDs have an option of something called "PCM stereo" which is better than CD for sound quality, but whether you can get that depends on the player.