Re: All Graphics Cards related queries here.
Anti - Aliasing  (AA): 
Is a technique used to remove the distortion from images. All images are   rendered by creating polygon shapes (primitives), and then joining  them  together. Now obviously a polygon does not have 'round' edges, so  we  will see jagged edges for non angular shapes. (Example a pipe or  wheel).  The graphic rendering system sees objects which will have edges  of this  manner, and apply an AA scheme to those portions of the image.  These  are basically again primitives which have a different level of  opacity  then the original image. These two are then joined at run time  (the  original smooth edges polygon+the AA supporting primitive) to  create a  non-jagged soft edge. 
So if you set 4xAA as the render method it is actually rendering 4   primitives per pixel on your screen at run time...! It is extremely easy   to correlate why the AA level immediately take a toll on the FPS. 
A method(s) used by GPUs is Full Scene Anti  Aliasing (FSAA) or Custom  Filter Anti Aliasing  (CFAA). You can say FSAA does the work in a full  batch per frame. It  takes the frame and renders it 2x or 4x times the  normal resolution, and  then down samples before it is pushed to the  screen. So at 4x FSAA each  pixel would have 16 super sample pixels.  CFAA is a technology that ATI  cards are using.
Anistropic Filtering (AF):
Is used to enhance the quality of 'textures' in images. It is used to   show greater details at angles which are distant or oblique to the   viewer. For example a farm house really far away. This is with respect   to the camera and not actually the polygon. This takes up a huge amount   of memory bandwidth. Lower resolution textures are used for objects  that  are further away from the camers (read player), to show the affect  of  distance. 
To quicken this process a logic of 'mipmapping' is used. For example if a   window is rendered using 256x256 pixels. Now you want to show this   window at a distance, what does one do. It makes the window smaller in   size --- but why use 256x256 pixels again..? So a shrunk version with a   high quality filter is used. Any many such textures are 'stored' at run   time, and re used over and over again. But this involves a lot of   calculations and is resourceful on the GPU. 
Now another issue arises. With so many mipmaps, when they are joined   together, the 'joins' will not look nice. You will get uneven surfaces   as distance is varied. We will see this as artifacts. This is corrected   by using Trilinear filtering, in this method each mipmap is filtered   along x-y axis but also with respect to the mipmap next to it. So as the   angle is changed the AF will start to vary.
You have a good GPU. Try to run games, with these setting as a variable,   you will start to see a difference. To notice AA, look closely at  edges  (no linear). And to notice AF look at distant objects. Yes these  are  important. They are the 
eye-candy drivers, and vary the   performance of the game.
Resolution:
1. 1400 * 900  = 1260000 pixels x FPS
2. 1024*768 = 786432 pixels x FPS
By using (1) you are getting ~ 40% more pixels on the screen. Of course   you will see better images, but the GPU has to do more work, so you   might see a performance hit.
And since you might ask about Tessellation too..here it is.
Here is a good link to an article.   If you are from a programing background you would understand the new   powerful features and capabilities which are available via the enhanced   API. This will take make game programing to a higher level, and greater   advanced features will be shown. Game programmers will quickly adopt  to  this new technology, and we as end users will see more game on this   codepath.
I personally feel Tessellation will 'change the way' 3D will appear on   our screens. Basically as of now 3D is rendered via polygons. Shapes are   drawn inside wireframes, and pieced together using multiple polygons.   And this wireframe is drawn over and over really quickly to shown   movement.  What Tessellation offers is that: these polygons can be   further subdivided automatically into smaller and more detailed shapes,   and each of these shapes can be 'controlled' for color, geometry. It   gives power for greater detail and image enhancement, with far far   greater control. All ATI cards which are >= 4xxx series have this   tessellation engine in-built. 
To see a classic example, go to 
this link, and click on the wireframe   buttons for the dragon and house. You will see the amount of polygon   counts increasing by a massive amount to render the same image. 
You could download the Unigine demo from the same link above, and run  it. If  you do not have Windows 7 and a GPU > HD4xxx, then run the  demo in Dx9, and press F9 to see the  wireframes. Its phenomenal.
And this is how a GPU functions:
The CPU is the central brain of the computer, and is managing   everything. The CPU infact send the 3D data to the GPU. When it does   this, it offloads a major task to the GPU.
The GPU is good at this, because the core is designed in a different   manner. It is not a 'manager'. It is a HUGE calculation engine, which is   extremelly data hungry ---> power hungery. Cause...
Basically a lot of mathematical calculations are done to convert from   one format to another. This can be off loaded to the GPU core. The GPU   core is efficient at doing this, cause it can calculate to really small   decimal places. Light vertex numbers are done using this. So the GPU is   really good at number calculations. 
They have the architecture of 'stream processors'. This is the SIMD   (single instruction multiple data) logic that the GPU uses. So multiple   data points are applied a single instruction set in one go, very   quickly. And these are all put in a pipeline -- which is the pixel   pipeline. So imagine a pipe full of data which needs to have floating   point calculations done on it. The data comes out of the pipe to the GPU   and the calculation is done. Now there are multiple pipes like this   which feed data to the GPU, which does the stream processing. GPUs are   rated with the number of pixel pipelines available to the GPU. 
This enables the GPU to quickly and efficiently process data. Perfect   for 3D rendering or format transformation. It does all this, renders the  3D polygon image, and renders them on the  screen. 
Now correlate all of that, and you are good to go.....! Hope it  helps...!