You should really try going to some SW websites if you are this interested. This has been an ongoing discussion for around 6 years. There's rumors, confirmed rumors, wild rumors, changes of heart by Lucas. It's endless. Here are several points germaine to this thread:

Lucas has said (although he keeps changing his mind on things) that he will not be putting the original version of Ep 4-6 on DVD, only the SE version with additional footage.

To my knowledge, because of the above, the original version has never been put into 5.1 surround by Lucas. Most bootlegs (of any movie) have DTS, recoded from DVD or LD. But for the original SW, this is probably just 2 channel. For the SE version, it may be a bootleg of the DD 5.1 channel created for the last set of LDs.

Lucas owns THX, which is linked with Dolby these days. Therefore, no Lucas DVD will ever have an official DTS track. (that's my assumption, so far true) Any Lucas film with DTS is a bootleg.

As Pronto said above, Lucas will finish Eps. 1-3, both theatrically and on DVD, before he will get to making DVDs of 4-6. What exactly it is he wants to update past the changes already done for the SE version I'm not sure. I haven't been following this stuff real closse, perhaps there are some solid rumors out there these days....