I think you are right there and you really, really don,t want to have to do this sort of thing every other year, so in my book, it pays to get the best quality you can now, but if you are really keen on being able to do something with the scans in the future, as emerging technology makes possible, then just don't save those scans as JPGs. The format is lossy and prepackaged to the extent where once you have saved as aforesaid, then it is almost a done deal with little further scope for alteration or improvement as time goes by. I personally, would save them in something like Photoshops PSD format or if they were really important, then as a .TIF file. Both of these are much larger than the JPG though. For up to a few hundred files, this isn't so bad - but for thousands?
And then we get into the discussion of how long a DVD image of a file is likely to last and at this point, I am retiring for a cup of tea.
Conan