My PC is now three years old and I am considering a new unit.  My interest has been sparked in building my own PC starting with a bare bones kit. (Cheers and Boos from the audience.)

ME: Retired electrical engineer and P. Eng. Handle most of my affairs, taxes, investments, eBay selling, and a little gaming on my PC. Close up eyesight, with glasses, still good.

POSSIBILITY:

Intel Core i7-4770K Processor/Asus Z87-A Motherboard/8GB DDR3 1600 Patriot Viper Xtreme Memory/Ultra 550W PSU/Cougar Solution Steel Gamer Case Barebones, package at a $539 price.

EXTRAS I THINK I NEED: Windows Software, keyboard & mouse, monitor, more DDR3, super display driver card, hard drive, DVD read/write.

WHAT DO YOU THINK: Go this way or buy a complete unit? Did I forget some extras? I (at lease initially) have items in red. When all done investment will reach $800, $1000, $1500, or more?

Happy to receive your views and opinions. Anyone had a disaster doing this?With your background as an EE, building your own desktop should be a cakewalk, it's not rocket science.

Biggest mistake you can make is to force the CPU into it's socket and possibly bend some pins, those little buggers cannot be straightened and mobo mfrs don't replace boards with bent pins.What strollin said is right on. Should not be hard for you. You can do it all with a screwdriver and a VOM.
One note. Modern design is moving away for units that use a lot of electrical power and make a lot of NOISE. So don't get to involved with a water cooled motherboard.
The actual act of building the PC is very easy, just take your time and if you get stuck, look it up rather than guessing.  The only way you can muck up is by forcing something in the wrong way or physically dropping/sitting on a fragile part.

The hard part is ACTUALLY getting the parts in the first place - http://pcpartpicker.com/ is a great site for this as it will warn you if any of the parts that you pick are not compatible.  It will also give you a "permalink" to let you share the list of parts you have chosen on here.

As far as your current part selection - It looks pretty good, the only part I would change would be the power supply (Not that much information about that ultra unit) - Something around the 550w mark is fine though, just get it from a good BRAND like Corsair (Not the CX line), XFX, Seasonic or Antec. This is a great option - http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=8592253&CatId=1483.  Getting an expensive PSU now makes a lot of sense as it's the one part that will never really become obsolete - For example, my current PSU has seen 3 Motherboards, 4 CPUs and 3 cases and is still going strong!

Don't feel the need to buy EVERYTHING in a bundle, you'll be fine if you use something like pcpartpicker and get us to check that everything is compatible.

As far as the CPU goes, the 4770k is a great chip without a doubt but is probably way more than you would need, only a few games take advantage of the i7 and even then the difference in performance is minimal.  Something like the Intel Core i5 4670k would do the job brilliantly.

As far as your extras go:

• Windows - Yes, you will need to purchase a copy of Windows - This will do the job fine: http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=8588430 (It includes a DVD containing the Windows installer and a sticker with your product key to be stuck onto the PC case)
• More DDR3 - For the tasks you have listed, 8gb is fine - Don't worry about getting more RAM at this stage, you can always add it down the line if you feel that you need it.
• Video Card - You will need a video card for gaming - For a mid range card that will handle all current games on good quality settings, you can't go wrong with the NVIDIA GeForce 760.  You can of course go up to something better like the 770/780/780ti if you wish, but this is probably overkill for gaming on a single monitor.
• Hard Drive - As far as the hard drive goes you'll know what capacity you'll use, 1tb is fairly cheap nowadays so I wouldn't go below that.  One thing to really consider is a solid state drive (SSD) - This does the same job as your hard drive but is a lot faster meaning the PC will boot and load applications significantly faster than on a traditional hard drive.  The trade-off is that SSDs are much smaller in terms of capacity (Around 120-250gb for a reasonable price).  What you may want to do is get an SSD and use that to hold Windows and all of your programs and then have a hard drive as well and use that to store larger files like music, videos and large games.  As far as SSDs go, you'd be best to look at the Samsung 840 Pro/Evo, Crucial M500 or something from Plextor (Avoid ones that mention 'Sandforce').
• DVD Drive - Don't fret too much over this, DVD drives nowadays are all pretty much the same.  Just make sure whatever you get is a DVD-RW drive, and get the cheapest that you find - The only real deciding factor between them nowdays is how the front of the drive looks.