OK so when I check my daily nutrition news this is what I see: food poisoning, http://www.washingtonpost.com/wp-dyn/content/article/2008/01/22/AR2008012200349_2.html. This article is pretty scary, it is about long term affects of food poisoning. Arthritis, kidney failure, and paralysis are very serious.
I knew about many of them b/c of my lab background. After seeing the picture from the clinical laboratory and then food prep side I know that food poisoning is nothing to play with. Most chicken in the grocery store has Campylobacter that is a fact. I don't remember the percentage of Salmonella contamination but it is "normal flora" in chickens. After processing sometimes some nasty Salmonella will be shrink wrapped with the chicken you take home from the store. And we all hear about the ground beef recalls due to E.coli.
Believe me I'm not saying to avoid buying meat. The easiest way to check if something is done is to get a reliable meat thermometer and cook your meat to the recommended temperatures. Once I got ours I wished I had bought one a long time ago. If you don't get a thermometer you will either undercook your meat and risk possible infection or overcook it and eat dry meat like we used to do. And little holes from the probe of the thermometer are far preferable to slashing the meat to see if it's done (also like we did pre-thermometer days). We use the CDN DTQ450 ProAccurate Quick Tip Thermometer, it is digital- 10 seconds to give a temp & is accurate. It runs about $20. If you want to spend more there is the $95 thermapen, it gives a 3 second readout and is also accurate (I reserve this one for my bread, but it would work for meat). I know you're thinking I don't want to fool with that, but it really is easier and will give you piece of mind about serving that hamburger or chicken.
Here's a link to a government site about recommended cooking temps: meat http://www.fsis.usda.gov/is_it_done_yet/. Use your common sense: wash hands after handling meat, use separate cutting boards for meat, and wash contaminated surfaces with hot soapy water.