[XanderF]

Normally, I'd argue that the "mip filter optimization" and "sample optimization" should be disabled, as they sacrifice image quality for performance.

HOWEVER...with the GeForce 7-series, it doesn't matter much. The texture filtering has hardware optimizations that are hardcoded, and while changing these settings does improve things a touch, you can't do anything about the hardcoded optimizations. This means that the image quality is ALWAYS going to be quite a bit less when compared the GeForce 8-series or Radeon X1K-series (note the "High Quality" tests which show the optimizations disabled).

Regarding the others:

• Conformant texture clamp (Hardware) - IIRC, this is an OpenGL-only setting (no effect on Direct3d, which the Silent Hunter series uses). Tribes 2, for example, needed this in OpenGL mode.
• Extension limit (Off) - IIRC, again, OpenGL-only. Been a few months since I've had an nVidia card, so don't recall offhand on these last two. Best I recall, they were there largely to resolve compatibility issues with some titles.
• Force mipmaps (None) - Some games don't specify a mipmap blend method. Thus, it defaults to 'none'. This lets you force higher quality mipmap (texture) blending when no method is requested by the game.
• Gamma correct antialiasing (On) - Very nice feature to have. Article on it, here. ATI cards have always done this, and nVidia cards just started offering it with the 7-series.
• Hardware acceleration (Single display) - If you have more than one display, this allows you to define how 3d games/etc is accelerated. Assuming you only have one monitor, or only play games on one monitor in a multi-monitor situation, this is the correct value.
• Ignore OpenGL errors (Off) - Again, another setting to work around various OpenGL issues.
• Negative LOD bias (Clamp) - Prevents games from setting a 'negative LOD bias', which in those titles (IIRC, "IL-2" is one) basically moves all the texture levels one direction out. This improves texture transitions and reduces 'texture shimmering' (where the ground or 'seems' between textures seem to...well...'shimmer')
• OpenGL threading (Auto) - Allows OpenGL calls to be seperated into multiple threads. Could be useful in a multi-CPU (dual core, etc) environment.
• Texture filtering (High quality) - This is actually just a 'catch all' setting. Note when you enable this, some of the settings above become disabled - IE., their behavior is controlled by this value collectively rather than letting the user control each one individually.
• Transparency antialiasing (Supersampling) - Another good one to have. This anti-aliases 'alpha textures' (textures applied to an otherwise solid object that have transparency to them. For example, the 'legs' of the cranes at the docks in the Silent Hunter series, your bridge railings, etc.) ATI calls this feature "adaptive AA", and you can see some 'before and after' pics of it in Sh3 in this thread. Anandtech offers an analysis of nVidia's Transparency AA modes on this page
• Trilinear optimization (Off) - As with the other 'optimization' settings, sacrifices image quality for speed. This is also controlled by the 'texture filtering' setting (IE., disabled when you use that one).
• Triple buffering (Off) - Effects OpenGL only. This allows the 3d application to have a 3rd 'back buffer' to render to rather than the standard 2 (IE., 3d applications typically render to a frame buffer, and this is 'flipped' into the display buffer for you to see the image. With this option enabled, there is a third buffer. In practice, the makes the game interface feel a TOUCH more sluggish - the responsiveness to input is now 50% reduced, obviously - but the average framerate is MUCH more stable. It's less likely that the game can 'gets ahead of the graphics card' in rendering needs, as the card keeps itself busy with an extra buffer over the standard method.
• VSync (Use application settings) - Probably a good idea to force this on. Essentially, your monitor has some refresh rate. This is the rate at which it redraws the screen (effectively locked at 60hz on LCDs, but you can't really tell as LCDs aren't re-drawing the entire screen every 'refresh', while CRTs do). V-sync being enabled forces the buffer 'flip' to wait for the next vertical sync (refresh on your monitor). This has the disadvantage of 'limiting' the game framerate to your monitor's refresh rate (IE., with a refresh of 75hz, the rendered image could never exceed 75fps, the extra power being 'wasted'), on the other hand, when flipping buffers at a different rate than the monitor is refreshing, you basically can get an image split some way down the screen between the two different (adjacent) frames. This effect is referred to as 'tearing' (and that's kinda what it looks like - two similar images, each torn in half, and layed next to each other).