I have all 5 series too, one episode has a problem where instead of zooming the scenes with CGI in and then clipping for 16:9, they just stretched them incorrectly.
I wish they'd put some cash in and redo all the CGI scenes in 16:9, be so good. Quality of the DVDs is a bit hit and miss because of this.
Top sci-fi series, still prefer this overall to the new BSG.