Also, the OT isn't only about Luke and the Skywalkers. That last scene of Empire is just as much if not more about how they're going to get Han back. This gets completely interrupted if you stop to watch the PT between Empire and Jedi.
I still say watch the PT before the OT or don't watch the PT at all.
On a side note, this brings back some good memories. About a year and a half ago, my friend and I sat down with a mutual friend who'd never seen the OT and showed it to him (it was my '04 widescreen boxset). Yea, it was the SE complete with wierd colors and sounds here and there but at least it was good picture and audio quality.....
Anyway, I think he mentioned beforehand that he'd "tried to watch the newer ones (the prequels) but couldn't get into them because they didn't make much sense" or something to that effect. So the three of us sit down to watch the OT. By the way, yes you can definitely still see the garbage mattes depending on your dvd/tv setup. They're as plain as day.
We finish ANH, our friend gets up and goes "next!" So we pop in Empire, that gets done, he goes "next!" By the time we finished Jedi it was the middle of the night. I'd also brought over TPM and AOTC (this was summer of '05) so I let him borrow those to watch. I asked him what he thought of them now that he'd seen the OT and he was like "yea, they make a lot more sense now." I'm assuming he also saw ROTS at some point.
I think this all goes a long way towards proving just how much better than the PT the OT is. You can jump right into ANH but you can't do the same with TPM. I think this shows just how much the prequels would've failed if they'd been made first, back in '77 and with the technology of the time. It's the story we really care about and no amount of SEing has truly ruined the OT, at least not yet.
Another story I'd like to share is rather brief by comparison. A friend of mine's niece is not two years old, but a few months ago he showed her the OT for the first time ('04 widescreen boxset). He noticed that whenever Vader was on screen she was making these wierd sounds with her mouth, but then he realized she was immitating his breathing! Watching it with her also reaffirmed my friend's opinion of just how awesome the OT truly is (even in SE form).