I have bought the aldi back to school pc and am looking for a new monitor around 20" sz. I've seen some samsung ones but the majority have a resolution of 1600 x 900 is that ok or should I be looking for a higher resolution?(I'm sure my current is x 1080 or something like that!) Also what does the 50000:1 mean? Thanks!
A higher resolution will give you more 'desktop real estate'. This basically means that you can have more Windows open side-by-side than a lower resolution screen.
1920x1080 res (with 16:9 aspect ratio) is full HD resolution & is handy to have when watching HD films, having two more-or-less full-sized Word documents opened side-by-side & for gaming - although some users prefer the more conventional 1920x1200 16:10 (seen in 24" & larger screens) for the latter. G
P.S. Always set a TFT monitor screen to its native resolution for the best possible picture & text.