How do I know if an HDMI cable is Category 2 or not? Does Best Buy carry any Category 2 cables? If not, is there an online resource listing Category 2 cables?

It will be marked on the cable package, and on the cable itself (near the HDMI logo).

The official HDMI terms are "Category 2" or "High Speed." "Simplay HD" is another independent lab that puts their logo on cables that are High Speed tested. You should look for these terms on the packaging.