Remastering the 77 movie is equivelant to adding effects, especially if it's aimed at HD resolutions.
they must have them remastered already, since they completely remastered them already for the dvds. They most than likely remastered the originals in high def and then added all the new special effects.
The VHS copies they came out with back in late 90s were remastered. These are of higher quality because they are on DVD.
Good too see the original versions getting released on DVD. I've got VHS copies (though, recorded from TV) of the original versions, and I have the VHS releases of the mid-90s rebrushing of the original trilogy. (Also used to have some bootleg DVDs of the Laserdisc releases of the remastered versions, but not sure where they went off to) Now I only have the 2nd remasters on DVD (the recent release), which in my opinion suffers from weird problems, like the "fixed" special effects have weird green boxes on them sometimes and such + they also did the weird replacing of Anakin at the end of the saga with clips of Hayden Christensen instead of the original shots of... whoever the guy was who did Anakin's appearance in the end. Will be interesting to see this new release though, maybe some fancy new bonus material too.
I'd wait until the HD Blu-ray or HDDVD before I'd want to fork out for Starwars yet again. If only Lucas had passed Episodes 1-3 to a decent director. I watched Episode 3 yesterday and it has some amazing scenes in the last 30 minutes. Shame the whole movie wasn't of the same calibre!