Rashiki

Both of those installs are pretty easy and straightforward. Start by removing your old video card drivers (start, control panel, add/remove programs).

Remove all the wires/connectors from the back of the PC, and bringing it to your work location. Remove both side panels (you only NEED one, but it'll be easier to see what's going on and makes routing wires easier) and then touch a bare metal piece of the chassis to dissipate any static electricity. Do this periodically thoughout your work so none builds up. It'll probably be easier to remove the video card first, so disconnect any power wires it's got and then unhook the little clip at the base of the motherboard where the slot is. It's on the back and is probably under the overhang of the card. This needs to be undone as the card is slipped upwards or you'll break something. Once you get it out, set it on a non-static surface such as foam or a new anti-static bag.

While the video card slot is unoccupied, start unhooking power wires. Grasp each connector firmly and pull with even pressure. Try to avoid rocking the connector, you might damage the receptacle or the motherboard itself. Many have little clips on one side, these are released by pressing your finger on it while pulling, much like an automotive electrical connector. Once you've got them all undone, it's 4 phillips head screws on the back of the case where the PSU is. Remove the outermost ones, as the inner ones (if present) are most likely for the fan. Bundle up the wires and slide the PSU forward into the middle of the case. If it doesn't move, check the top of the case on the inside for more screws. Some PSU's slide on rails, make sure you're clear of them.

Install is pretty much reverse of removal, just make sure your extra wires are clear of any metal. I like to use zip ties and bundle them at the top of the case or in an open 5" bay where they don't impede air flow.

The connectors are pretty straightforward, mostly one connector will only fit one receptacle. Make sure all the connectors are hooked up and that none of the wires are chafed/exposed. Put it all back together, fire it up and install your new video card drivers!