I got one of those blue LEDs from radio shack too. those things are bright as hell!!
To install it in a 7237... you first gotta take off your front bezel and remove the whole LED unit from the front of your case. Once it's detatched, use some pliers and simply pull lightly to slide the old LED out. Then just stick the new blue ones in. However, the new blue ones are bigger, so its gonna be a little harder to put it in (don't worry, it fits on mine). Once you push it in, turn it on and you've got a new BLUE LED light.
To install it in a 7237... you first gotta take off your front bezel and remove the whole LED unit from the front of your case. Once it's detatched, use some pliers and simply pull lightly to slide the old LED out. Then just stick the new blue ones in. However, the new blue ones are bigger, so its gonna be a little harder to put it in (don't worry, it fits on mine). Once you push it in, turn it on and you've got a new BLUE LED light.