A little pre-swap prep goes a long way.
1) Layout everything you'll need, like it was a surgical operating room. Check what screwdrivers you'll need, if you need any new cables (like HDMI or internal power cables). I highly recommend getting a can of compressed air to blow out the years of dust that covers your motherboard and fans. That's right, I can see into your computer case.
2) Before you shut off your computer, download the latest drivers from the manufacturers website (AMD drivers or (NVIDIA drivers). Generally these will be newer than the drivers that came with your card. Installing the supplied drivers won't hurt anything, but it adds an extra step as you'll still want to upgrade to the latest drivers eventually.
3) Depending on your operating system, find where you uninstall the hardware (Control Panel>Hardware and Sound>Device Manager, or similar) and uninstall the graphics card. This will likely drop the screen resolution to 640x480, but it doesn't matter as we're leaving.
4) Shut down the computer.
5) Harness your chakra. No, really. Ground yourself by touching a metal part of the case.
6) Unplug the computer.
An HTPC graphic card can really save your expenses while having the fastest pc. The last graphic card that i have used was Asus ATI Radeon HD6450. And according to some reviews, it is always on the top list and it really works fine for me.