First off, I hope everyone is having a good night!

My question relates to BitCoin and personal security. How are you protected from someone trying to rip you off?

For example purposes only: Say you move BitCoins from your desktop wallet to an online store to buy an HDTV. The BitCoins leave your wallet...but the store says you never sent them (when in actuality you did, but they are lying to you).

What options do you have? Is it merely your word against them? Is there some sort of "trace" that you can show the legal authorities?

Thank you for reading.