The Day The Earth Stood Still (2008), The Day The Earth Stood Still (1951)

I watched the second version of this film a few weeks before watching the original, and geekishly enjoyed juxtaposing each of the films values, forms and conventions. Both films portray values that are very contemporary at the time of their theatrical release. Issues such as the war in Iraq, and environmentalism take the main stage in depicting humans' vices in the remake, and in the original it is blatant that the cold war is in full force and that the enemy under question is from the Soviet Union. I find it pretty funny that both wars in Iraq and against the Soviet Union have so much in common, it really illustrates how America seems to be at war with someone at any point in time (they just can't get along with everyone).
In terms of visual depiction the remake is as high tech/CGI as you can get. While this does not ruin the experience of watching the movie, I must say I prefer the low fidelity graphics of the original. The graphics are not even that bad in respect to the technology that the filmmakers were dealing with at the time. They are very simple, and a lot of the effectiveness ends up being delivered through the spooky cinematography and eerie music.
The family unit and characters' roles are also different in both films. For example, take the female lead. In the original she is a humble single mother, working as a secretary, who is dating a decent man. In the remake the same character is also a single mother (but the son is not biologically her's), she is a ground breaking scientist, who caries herself with sophistication, and is more focused on her career, than to have a love life. I think this is interesting how vastly the same character has evolved. It certainly is done to illustrate how women have different priorities in their lives now, than they did 60 odd years ago.
In terms of recommending, the original is definitely a classic, and will probably be remembered for a lot longer than the remake. Both were enjoyable in their own capacity, but I say if you have to choose go for the original.