EDIT: All new versions will now be released at the official site - http://sourcegl.sourceforge.net

What is RInput?
RInput is a program made by a programmer that goes by abort, that reads the raw input data from your mouse and feeds it directly to the cursor/crosshair position in game. It serves as an alternative to in-game raw input or allows for raw input in games that lack it. For games that have a raw input option, it should be turned off for RInput to work (m_rawinput 0 for Source games).
Why use RInput?
I believe the main issue with Source's m_rawinput 1, even though it collects true raw input data, is how it is buffered by the game. I've read somewhere before where someone who knew a lot more about it than me was talking about how it was related to m_rawinput 1 having poor time-stamping of the raw input data in relation to the framerate, so the buffering can be quite variable in comparison to the way frame-rendering is buffered. At sufficiently high refresh rates and FPS, this tends to make mouse movement feel 'disconnected' in a strange way with what you are seeing on screen. Many players including myself find using RInput (without an fps_max cap) to be better performing than Source's raw input implementation.
What is digital vibrance?
Digital vibrance is an NVIDIA option that is subtly different from a straight saturation adjustment. It can be best explained as something like, digital vibrance is the intelligent saturation (when increased) or desaturation (when decreased) of the display image on a pixel-by-pixel basis, based on a given pixel's original saturation value.
Why change digital vibrance?
Digital vibrance can be more useful for certain gaming situations than a plain scaled saturation adjustment because it will decrease the dynamic range of saturation for a given image, which can help make certain colors and shades more noticeable relative to their environment when compared to the unaltered image. As an example, for DV @ 100%, both Ts and CTs stand out much more to my eyes against the brown/yellow backgrounds and floor on Dust 2.
Is it VAC safe?
In a word, yes. But see the README for a longer discussion on VAC.

What is RInput?
RInput is a program made by a programmer that goes by abort, that reads the raw input data from your mouse and feeds it directly to the cursor/crosshair position in game. It serves as an alternative to in-game raw input or allows for raw input in games that lack it. For games that have a raw input option, it should be turned off for RInput to work (m_rawinput 0 for Source games).
Why use RInput?
I believe the main issue with Source's m_rawinput 1, even though it collects true raw input data, is how it is buffered by the game. I've read somewhere before where someone who knew a lot more about it than me was talking about how it was related to m_rawinput 1 having poor time-stamping of the raw input data in relation to the framerate, so the buffering can be quite variable in comparison to the way frame-rendering is buffered. At sufficiently high refresh rates and FPS, this tends to make mouse movement feel 'disconnected' in a strange way with what you are seeing on screen. Many players including myself find using RInput (without an fps_max cap) to be better performing than Source's raw input implementation.
What is digital vibrance?
Digital vibrance is an NVIDIA option that is subtly different from a straight saturation adjustment. It can be best explained as something like, digital vibrance is the intelligent saturation (when increased) or desaturation (when decreased) of the display image on a pixel-by-pixel basis, based on a given pixel's original saturation value.
Why change digital vibrance?
Digital vibrance can be more useful for certain gaming situations than a plain scaled saturation adjustment because it will decrease the dynamic range of saturation for a given image, which can help make certain colors and shades more noticeable relative to their environment when compared to the unaltered image. As an example, for DV @ 100%, both Ts and CTs stand out much more to my eyes against the brown/yellow backgrounds and floor on Dust 2.
Is it VAC safe?
In a word, yes. But see the README for a longer discussion on VAC.