Yeah, when I read your original post, I was figuring, "They totally gave him a floor model in a box." Somehow I had a bad feeling about it.
Just so you know the problems with the gen-one 360s were due to a manufacturing error, not Microsoft. Odds are you can return it to the store if it hasn't been too long.
What do you mean by DRE, though? Cause the red ring of death doesn't necessarily mean that's the problem, and if it specifically gave you a disc read error instead of the red ring of pain and suffering, you can probably just clean the disc or the drive and fix it.
Either way I would DEFINITELY bring it back to the store.
It's also possible that it needs updating to its software, as there have been a lot of changes to it since it was first released and some newer games might have trouble. Plug that sum-***** into the internet and get the updates, see if it helps, then take it back to the store.
And don't ever, ever, ever consider buying a used console.
EDIT: if it's just a disc read error, that usually just has to do with the disc being in a little wonky, open+readjust+close should solve that. It spins at insanely high speed, remember, so it's only natural that if it's slightly off-center in the tray it could spin wild and cause a DRE. Unless of course you are using it lying down instead of standing...
Either way get xbox live and download the demos like crazy; you'll learn which games you want to play real quick. Almost all of the games, despite ESF's hating on the M$, are really good--it's just a matter of what your into.
