I am trying to decide between Vegas + DVD or Premiere. I understand that either will probably be just fine for what I am going to do. I do have some (although not tons) experience with Photoshop 7. So my question, would I benefit from sticking with another Adobe product because of a similarity in interfaces or not?

Your BEST bet is to download the demo of each and try them. Also, look at the forum communties of each and see what the current "problems" are and how helpful other users and tech support are.

Vegas seems to be more powerful than Premiere Pro at Photoshop-like tasks, although you can always export an image sequence for Photoshop to process if you need Photoshop effects.

I like Vegas more. It's super powerful (can do lots of video effects and is the best NLE at audio hands down) and stable. I think the bad things about it is that it renders slow and that you have to figure out how to organize your media.

Premiere Pro is kinda like Final Cut Pro for the PC except a lot buggier. You might want to wait for the patches for it to come out first. If you are already familiar with the Avid/FCP/Premiere interfaces then Vegas will make no sense at all to you. The similarity in Adobe interfaces doesn't really help.

Try out the demos! I tried to work for a year with Premiere but
it just seemed to be wrong for my mind (first time I fired it up
it asked me which editing method I wanted to use... errrr. what?).

So althought I was a bit used to the Premiere interface I learned
Vegas myself in one day. It just seems to work a whole lot better
with my mind.

Trying out the demos of both product will give you the ability to
see for yourself what works. Do make sure you have something
to really edit on both packages, because just looking around isn't
enough!