Yes, I'll probably be playing at that resolution or lower than that cause my monitor isn't very big(It's square, not widescreen).
I know playing BF3 needs a good card but can't I even play AC:Revelations?
Sure, you can play any of those games. Just not at very high resolutions. And with a minimal amount of eye candy turned on. If you try to use higher resolutions, your framerate will drop to where the games will be unplayable. I agree with cutebeans, use the savings in dropping your memory to 4GB, and put it towards a better card.
The higher the resolution (the more pixels and texels the card has to address), the more work the card is expected to do. Right-click on the Desktop and click on 'Screen resolution' to check what you are using.