Hello and welcome to Bleepingcomputer.
First of all the processes you need to worry about, the number one you need to worry about is whether your house wiring is properly Earthed.
I do not know if you rent or own the building you live in.
If you rent, it is up to your landlord to fix the problem.
If you own, it is up to you.
By using the word properly Earthed is to say the Main supply feed to your house wiring, must be properly grounded to Earth as it enters the building, this is done by driving a copper or steel rod deep into the Earth about 4 feet deep.
Attaching a copper cable to this rod and then attaching this to the house wirings 3rd wire, this is the ground wire, it is commonly a bare uncoated wire made of either copper or aluminum, this wire then connects to the 3rd prong of most house wall outlets, in the USA this prong has an "U" shaped prong while the other two are flat and wide, one prong is slightly wider then the other so it only fits the socket one way.
Your computer comes with a power plug for your PSU that has 3 prongs, it can only be plugged into the wall outlet one way, the wall outlet should be grounded through the 3rd prong.
If your house wiring is very old and out dated, there is the chance the outlets do not have polarized plugs, there is also the possibility someone did not wire the hot and neutral wires properly to the wall socket.
To properly address such issues, purchasing a device that plugs into wall outlets to determine if the socket is wired or grounded properly can be purchased.
Radio Shack carries such a device.
You also need to be concerned about your Internet connection, how are you connecting? Cable TV? Telephone line?
You need to make sure that service is properly grounded as well.
Also another phenomenon is when the air is very dry, static electricity becomes a big problem, your touching something that is grounded to Earth can cause a temporary discharge of positive or negative IONs from your body to the grounded device, or to a device that is charged differently then your IONs, opposites do attract in a case like this and the result is electricity flows.
Some power strips do offer some assistance in determining line conditions, they come with status lights that indicate if the lines are reversed polarity or if they are properly grounded to Earth.
As long as everything is properly connected inside of a computer and grounded properly and the house wiring is properly grounded, there shouldn't be any reason to connect an extra grounding wire to the computer case.
It can be done, but should not be necessary if the things I mentioned above are taking care of.
If you are interested in purchasing the device I mentioned I will provide a link to several such devices here in this Google search link: http://www.google.com/#q=electrical+outlet+analyzer&hl=en&biw=1263&bih=641&prmd=ivns&source=univ&tbm=shop&tbo=u&sa=X&ei=rtDFTfKNNYH20gH47tjtAg&ved=0CH8QrQQ&bav=on.2,or.r_gc.r_pw.&fp=4a6afda2e5e8ee6f
Edited by MrBruce1959, 07 May 2011 - 06:10 PM.