If you don't think it is necessary to flashingflash a radio then don't do it. At least I heard that it will not make any difference to your phone storage and speed. But somehow if you have connectivity issues like dropdropped calls, WiFi connection not searching or GPS isdoes not seem to work thanthen surely you need to flash the radio otherto another version than you are using at the moment.
If you want to see which radio your phone is working on is go to settings > About phone > Baseband version > See the last some digits and then search for your phone Like HTC desire lastestlatest radio etc..
Note: I Recommend you should read more about Radio before flashing it. Sometimes there is a chance to brick your phone but don't worry if you have searched enough of it you willare not going to looselose anything. At least give a weekend or two to search for tutorials on forums like XDA, android centralAndroid Central, Google, Wiki etc..
Happy Flashing