If you're running Windows XP you can get the bit rate from windows itself. Open a folder with mp3s, put that folder into the "details" view (click on view on the menu bar and choose detail). Above the list of files in the folder will be some headings (name, size, etc). Right click on this and a pop up will list all the possible headings. Bit Rate is one. Select that and you're done.
This doesn't tell you the Khz of the file, however. It's safe to say that most music mp3 will be at 44 Khz, but one never knows.
There is a freeware program that will tell you both the bit rate and the Khz rate. It's called dbPoweramp convertor. It integrates with windows explorer so that when you select an mp3 file with your pointer the bit rate, Khz rate, headers, etc will display in a pop up.
It's available at http://www.dbpoweramp.com/
There are also mp3 playing software that will display both numbers. I use
QCD, available at http://www.quinnware.com/index.php