Not that I am any fan of the zombie craze but... biological weapons unleashed in a WW III scenario could very well lead to people who are somewhat zombie-fied, say by some form of weaponized CJD (human form of mad cow disease). Odds? Very low... but definitely not zero.
Anyway, a wise person prepares for the future, whether than be good or bad. We assess the possibilities and weigh our options. Once we have ordered the possibilities, we allocate our available resources towards these potential problems in roughly the same percentage as we assign their possibility of occurrence.
That said, I would rate the possibilities as:
Highest: earthquake, flood, or storm that causes heavy damage to my local area, US financial collapse due to high debt and crummy national economic policies, serious inflation that decimates paper currencies
Moderate: outbreak of war, widespread disease / plague, collapse of electrical grid due to poor maintenance, heavy demand, and insufficient capacity
Low: possible EMP either as terrorist act or solar flare
Least: meteor impact on Earth, polar shift (?), ice age, etc.
During the initial stages of most any SHTF scenario will be the time to keep our heads down and not attract any unwanted attention to ourselves... security through obscurity, as it were.
Assuming that one survives the initial part of a possible SHTF scenario, there will come a time when trade / barter resumes. People have resources and needs to be met, so they come together to trade what they have for what they want or need. This is the point where silver and gold will be of use. Both have been recognized for 4,000+ years as money... something that everyone values and will trade for because they know it can be used to buy the things that they want or need. Besides... it is FAR easier to carry around a pouch of gold and silver coins when shopping than to carry around a cow, a stack of lumber or fire wood, or several sacks of wheat.

Other things will also be of great utility and highly desired as trade goods. These things include: hand tools, ammo, fish hooks, needles & thread, food of any kind, water purification tablets, medical supplies, matches, etc.
Then, of course, we have labor, which is an intangible. You need a cord of wood cut and split. I need some of your garden produce. We haggle, reach a price, and make the trade. I get the produce and exchange my labor for it while you get the wood you need to stay warm this winter. In cases where one of us doesn't have a trade item that the other wants, a few silver coins can be exchanged to settle the debt.
The bottom line is this: is it better to be prepared for future difficulties or not? If it is, then you know what you need to do in your location and estimate of the possible scenarios. If not, then just do whatever it is that makes you happy.
