Using ping will only tell you instantanious lag time to the IP your pinging. (leave that to gamers where latency matters)
A test file will only tell you how fast 'you' can access a file download - basically if a box has 1Gb connectivity and all that bandwidth is accessible all the time you'd need a 1Gb line to test it to get an acurate result, some hosts point you to a test file on a 'very' quiet server

or an empty file which compresses giving a false rate.
In short test some sites on the server you need to test, a couple of static and a couple of forums is usually a fair test

that way you'll get a realistic idea of responses to requests for pages and database info. (only a fair idea though)