I think you must realise that there are multiple exchanges involved in the 'market' which these traders operate in. The speed of placing an order is important but the information about other related prices and indices is also very relevant. Getting this information 60ms before other market participants would give you a huge advantage.

60ms would make no difference to how fast a human can make a decision. This is for automated trading.

So can't they put a computer near each market that would get the relevant information quickly and place the order quickly as well?

The programs would need information from markets around the world, not just the closest to it. So if you're in Japan, you'll use information from the European markets to make more educated trades and vice versa.

Ah, that makes sense. Thanks.

the computer would need data from the other exchange(s) as well, not just the one its nearest to

I didn't think of that, thanks.

Although aren't the exchanges open at different times? I guess there is some overlap.

If you look at the bottom of the 24 hour graph here (http://www.kitco.com/charts/livesilver.html) you can see the opening hours for different exchanges around the world. You can see that for a few hours London, New York, and Hong Kong or New York, Hong Kong and Sydney are open. It's quite interesting and of course a bit of a headache if you have to work in a multi-timezone system.

In addition to equities (stock market) which also have extended trading hours (pre and post market trading) there's also a massive market called futures and another called currencies which are opened nearly 24/7. A ton of money is traded in both those markets.