Whats more accurate? MtGox in my Multibit wallet says 1btc=730$ while preev says 1btc=691.80$ Thats about $40 difference, so whats more accurate or should I say ahead? Thanks!
There is no one exchange rate, and no value is more accurate than any other value. Mt. Gox is the most quoted but its problems make it an outlier. All the exchanges operate independently, so trades occur at different prices. Although there is some amount of arbitrage, the difficulty of transferring fiat between exchanges prevents the difference in the prices from narrowing.