I am using Linux with the following hardware configuration:
- Intel Core i7 3.4GHhz 4770k
- MSI Z87 MPower motherboard
- MSI GeForce GTX760 2GB DDR5 graphics card
- 1TB hard drive
- 16GB RAM
Do I need a graphics card driver for Linux?
Yes and no.
Linux is perfectly happy to run even without a video terminal at all (consider serial console or "headless" setups).
Linux is perfectly happy to run in 80x25 character mode with 16 colors.
However, it would seem pretty wasteful to have a high-end graphics card doing nothing but displaying text at what amounts to 720x350 pixels screen resolution with almost-just-barely individually addressable pixels. This is a 1984 level of technology.
X11 (usually implemented in XFree86 and these days more commonly Xorg) needs a driver to be able to use the graphics card to display graphics. It can use the VESA framebuffer support of the Linux kernel, or it can use a specialized driver that is able to make better use of the specific graphics card installed. As peterph points out, the VESA driver is very slow, but it works with basically anything that can output to a graphical display and hence is a good fallback when everything else fails or when you have no idea what hardware you're going to encounter (such as in an installer environment).
This means that the question you should be asking is "do I need a driver for the graphics card to function in X11 graphical mode?". To answer that, yes, you do, and X11 comes with a pretty decent set of drivers that especially in concert with the kernel's framebuffer support allow you to use the basic functionality of most graphics cards available today. You might not be able to use the card's full potential (for example, hardware 3D acceleration), but then again you might. That depends on the capabilities of the particular driver that your distribution of choice installs by default for that particular card at the particular time, and as this can vary widely among distributions and releases, the only way we'll be able to answer that would be if you ask a specific question such as "is Ubuntu 13.04 able to use the full potential of the GTX760 out of the box or do I need to download a separate driver?".
This is basically what Ignacio Vazquez-Abrams's answer is about. Chances are that the driver that is installed by the distribution's installer is fairly well supported by that distribution, even though it might not fully support the hardware's capabilities. Hence the suggestion to just try it out first, and if it doesn't work the way you want it to, then you can look for an alternate driver.
You do, in your case of a nVidia card you have basic choice of the open-source
Apart from that, it should be possible to use legacy
Yes, you do. But you may be fine with the one that comes with your distro. Give that one a try for a bit, and only if it doesn't suffice will you have to look for a different one.
If you're already using linux with that configuration then you already have at least the default open source graphics driver installed.
If you want better performance and more features you'd want install the nvidia proprietary driver.