please use your own definition of old or classic :)

Speaking for myself the following comes to mind :

ET
The Edge
Citizen Kane
Back to the Future 2 an 3
All of the spaghetti westerns

Unfortunately the internet has has graciously supplied me with significant spoilers to the first three. The first one I don't mind so much, but I really would've loved to see the 2nd and 3d one without spoilers :(

How about you?

edit : oh yes and I've definitely got to add
Ben Hur
Lawrence of Arabia

Godfather
Godfather 2

Been so long since I've since 2001: A Space Odyssey that it will be like watching it for the first time.

Since when are Back to the Future 2 and 3 "classic/old films"? :P

Since it was 27 years ago it was released that was before a lot of GOG customers were even born.

My English is terrible today, please have some understanding.

Okay so it's old. :P The first movie IS a classic. Not so sure about the 2nd and 3rd but I don't want to get into a tiff about it, so I'll drop it. :D

They were passable entertainment, good enough on the telly after a hard day's work (ugh! I still remember working 12h that day).

Yeah same here. Currently I'm waiting for the right time to watch it. Not sure when that will be, but I'm sure one day I will wake up and realize 'today is the day...' Shh man don't ruin it for me. The first one is a timeless classic and number 2 and 3 will be too dammit!!

#3 is good, bordering on really good.
#2 is CONFUSING :P

Patton
Zulu
Bullit
Duellists
A Passage to India
12 Angry Men

That's just some of them. And there's loads more classics I feel like I should watch, but don't really look forward to it (like Full Metal Jacket).

I don't want to hype this too much, but BEST CAR CHASE EVER!

*gasp* thud!

I'm not much of a Kubrick fan. The only thing Space Odyssey is good for is simulating time dilation. It's just over two hours, but feels like two years.

No Shining?
No Clockwork Orange?

I liked the Shining. Not loved, but I thought it was good. Then I watched Barry Lyndon and basically gave up on Kubrick. It's soooo looong. Soooo boooooring. The narrator never shuts up. Maybe every frame of it is perfect like a painting, but as a movie it just sucks.

I haven't seen it in many years, but another thing I thought it did very well, especially compared to other sci-fi films : the sense of hopeless isolation. No mention of lightyears, no obscure hidden corners of the galaxy, no weird alien locations in another galaxy altogether. No, just a straightforward journey to a well known point in our own solar system, Jupiter. And yet, compared to all other scifi I've seen, the safety of Earth's atmosphere seemed the furthest away to the crew of Discovery One.