The following are the things to consider when purchasing a new card:
-Motherboard Compatibility (AGP, PCI, PCIe, PCIe 2.0 x16, PCIe 2.1 x16)
-Graphics Ports (most new video cards now include a VGA to DVI adapter, so this is less of a worry)
-Power Supply (it needs to have enough to power the card and everything else)
-Case Space (with newer high end cards, there can be little room left. I have a N260GTX in a Full tower case, and it BARELY fits. Make sure to measure your case)
-Money vs Power (This is for you to determine, I WILL NOT cover this)
-New Graphics Card
-About 30 minutes
-New video card drivers (on CD or downloaded beforehand)
If you have onboard graphics on your motherboard, you should disable this is BIOS before you install your new card.
To do this, you must restart your computer. When the OEM logo (or BIOS) comes up, press one of the keys shown at the bottom, usually F1, DEL, ESC, etc. It should be labeled, ENTER SETUP.
Navigation is done with the arrow keys here. Scroll to the advanced tab, and look for a graphics setting, and disable it.
NOTE: This CANNOT be done through Windows (or any other OS), it MUST be done through BIOS.
1) Remove your old graphics card drivers. There are a few ways to do this, but I will cover the default Windows way:
a) Open Device Manager (Computer, right click Properties, Device Manager)
b) Select Display Adapters
2) Turn off your computer, and unplug the power cord from the Power supply unit. It is also a good idea to remove all the plugs from the back of the computer, and take the unit to a non-static workplace, like a wood workbench. Carpet and metal is not recommended.
3) Pull out the old graphics card. Some motherboards (and cards) have a release catch on them, usually under the card, to the inside of the motherboard.
4) Put in the new card. Push it in with firm, steady pressure until it drops in snugly. Wiggle the card GENTLY to see if the base is loose. Plug in the power plug from the PSU (not all cards need this, some use one 6 pin, some one 8 pin, some two 6 pins, some two 8 pins. Look at your card and your manual to find out)
5) Screw the card into the case, and put the case back together
6) Turn on the computer, and install the new drivers.