Geday thepainter,
K - ive looked at and tried heaps of these suckers.
Many are just toooo damn hard to set up as good as they may be - you nned to be a programmer no matter how easy they say it is :)
Dynamicdrive for simple scripts of all kinds of simple slide shows - theyre good and work.
For a Gallery - urrrr - Im using SPGM, a JS system --see my site :)
Easy to set up as either flat file or database if you have no mysql. It was ok to setup -well kinda easy. You can set heaps of parameters and choos the popup size up to full screen. There are heaps of galleries - but tis a minefield of bodgy jobs.
Gallery is good but have you tried to understand that installation? - cheez.
Hope that helps.

Keep well.