Could be that the previewsettings of your previewscreen in premiere has been set to draft quality, something you can change with the very small button in the upper right corner in the previewscreen (That's the case with version 1.5, don't know how 2.0 looks.) though that doens't make that big difference.
Maybe you could do a screenprint from your general project settings so we could have a look if they are correct.
If you are worried about the quality on dvd, why don't you make a dvd to check how it looks on a tv? And if you are running a business and want to impress your clients then continue using wmm is not a good idea, the program is way to limited to do some decent editing.