Static buildup is very dependent on relative Humidity (RH). RH at or below 30% can be deadly. AND winter with it's very low RH is just around the corner, Unless you live in the "Down Under"
Some of your components operate at Less than 15 Volts in fact Ram is normally 1.5 V and CPUs are around 1 Volt for operation., You can build up in excess of several hundred Volts and Never Know it. You do NOT even have to touch the pins, just sticking your pinky Very close you risk either turn it into a paper weight, or create a condition known as “walking wounded”.
Do not recommend setting ESD sensitive items on a glass table and NO the metal legs will NOT prevent glass becoming charged. The glass can build up a high static charge that can damage a component part. Case in point: One poster about a year ago placed a Hard disk drive on a Glass surface and wiped out the HDD.
My recommendations Is to place a conductive surface on glass table. DO not remove any other components from antistatic bags. Install PSU into case and connect power cord to PSU (PSU rocker switch should be off. I normally use one of those power strips and turn it off and plug PSU into it. Put on wrist strap and connect to Un-painted metal on case. Know you can start removing and assembling the components.
Bottom line, for 10 Bucks it is much better to be safe than sorry.
Quote: "Use a plastic floor mat if you're that worried." LOLs thats like jumping from the fring pan into the Fire. Plastic is a NON-conductor and an excellent source of static build-up.
And Yes I'm ESD certified and have to attend manitory class every two years.
Getting away from the computer advice and the root cause:
if you have a lot of static in your house, it indicates your humidity is likely too low.
If you go to hardware store and pick up even a cheap humidity meter (hygrometer) this can confirm it. Should be like $10 (and will tell you the air temp too).
Then if you really want to solve your problem, then perhaps getting a humidifier is what you really need.
In a short term, if you mist around some water from a spray bottle (onto the carpet not onto your computer parts), or take a hot shower with your door open, to increase the moisture, you may suddenly find no more static shocks. That being said, previous advice to just guard against static should be fine too