for me the bottom line is, occasionally an iced coffee or energy drink will help me a bit, even appear to make me play better, and give me a pick me up when i need it... but it's not reliable at all so OCCASIONAL is the key word.. other times it will make me slightly nauseated.
it's hard to generalize about the caffeine content of coffee. depends on the roast, cup size, bean, etc. a grande regular coffee at starbucks is 330 mg (someone maybe already posted this), more than any energy drink i believe... i believe NOS is the strongest energy drink at 260 mg.
new harvest organic french roast is sublime, highly recommended