I do all of my building on my carpeted floor. I always wear socks. I never stand up as I work on the floor. Static can be serious, but it's not as common as it may sound. Just touch something metal (case) before working on the motherboard. If you're real concerned, get a grounded wrist strap. They are ~ $10.
A wood or plastic table is all you really need. The biggest thing in component safety is this rule, follow it and youll be fine. Only take your compontents out of their bags the moment you plan on installing them. If you need to set it down do so on a hardwood table. Antistatic bags are designed to discharge the static on your body when you pick them up. If you then touch something else after holding onto the item you can then cause a problem. Just hold onto a metal part of your computer system for a few seconds and then pick up your part and always avoid placing your fingers and hands on connectors and microchips.
Reference antistatic Bagging. The outside is conductive very high ohmic value to dissipate a static charge. Inside is non-conductive which prevents any charge on the outside being transfered to circuit on inside of the bag.
Added: High ohmic value => 20 megohms per square in which should be safe to lay a circuit card on.