One more thing, what cables will I need to buy? Surely I'm not lucky enough for everything to come with required materials.
Depends on what you have.
A retail motherboard will typically come with 1-2 IDE cables and 2-4 SATA cables.
A PSU will obviously come with all the cables it lists in its description (several 4 pin, 6 pin or 6+2 pin, a 4 pin CPU, and a 20+4 pin ATX, as well as a few SATA plugs). Usually it's all one mess of wires unless you're buying a modular PSU.
A HD, if it isn't an OEM HD, may come with a 4 pin molex to SATA converter (although your PSU should already have SATA connections, making this irrelevant). OEM HDs may or may not come with this cable.
A video card will usually come with a 4 pin molex to 6 or 6+2 pin PCI-E adapter, as well as typically including a DVI to VGA adapter and a crossfire or SLI bridge. Again, you likely won't need the power adapter since a newer PSU should already have 6 pin or 6+2 pin connections.
The case will have cables inside it already for power switch, reset switch, HD LED, power LED, possibly USB ports or audio if the case has them.
you almost certainly should not have to buy any extra cables; maybe if you want to connect your computer to your monitor via HDMI (instead of DVI or VGA, assuming the monitor supports HDMI) or something like that... but as far as the case itself goes, you should have all the parts you need.
As far as plugging things in to each other:
You will need to ***** the motherboard down to the case. Don't forget to use the standoffs (small metal screws with receptacles that hold the MB at about 1/4" off of the case itself) unless you want to risk frying your brand new motherboard as soon as you turn it on. The screws and standoffs either come with the motherboard or the case; I'm having a brain ****. Pretty sure it's the case. Could be wrong.
Motherboard and video card both physically snap in to the motherboard.
You will either need an IDE cable or a SATA cable (SATA is the current standard, older parts will use IDE) for your optical drive and to connect the HD and DVD to the motherboard. (Comes with motherboard)
If you're using a floppy drive, you'll need a cable for that too. (Usually comes with motherboard. May not.)
You will need to connect the CPU to the motherboard, and then put the heatsink/cooler on top (don't forget to take off the piece of plastic under it, unless you like the smell of burning plastic and the notion of possibly buying a new processor to replace your dead one.
You will need to connect the CPU heatsink fan to the motherboard (typically right next to or very close to the processor; it's a small 4 pin plug).
You will need to connect the power supply to the video card (6 pin), hard drive, DVD, motherboard (a 20+4 to the 24 pin on the motherboard and another 4 pin to the 4 pin spot), and any fans you may have in the case.
Make sure everything is screwed firmly into place, make sure all cables are secure, make sure the CPU cooler is firmly secured to the CPU, make sure there are no pieces of protective plastic that need to be peeled off of anything, make sure the switch on the back of the PSU says 110/120 if you're in the US; in other countries with different voltage, make sure it says 220 or whatnot instead by moving that switch over. Never ever try to turn it on with the switch on the wrong voltage "just to see what happens" unless you have the money to fix "what just happened".
Beyond that, you should be golden. Edited, Jul 7th 2010 4:54am by Mikhalia