You don't need to buy Adobe software. Adobe lists superseded software on its website that can be downloaded free of charge and even updated.
Among them is Photoshop, Lightroom, Elements... the usual inflated and over-featured industry-standard packages. Personally Elements does the job well enough for me, as does Irfanview. 4x6 prints don't require a very big scan size; enlarge them to 300% on-screen to despeckle/dust.