No problem on the response! That is what we are here for!
As for your dilemma, I am afraid the answer remains the same. On Nextel, no matter what you do, you will never be able to see who a SMS is from...
Something that may make you laugh, check this guy out that is feeling the same pain as you. More importantly look at the last one on his list. How would you feel receving that SMS... SMS on BlackBerry 7510/7520
In all seriousness though, if you want to know who an SMS is from, you gotta get off Nextel (to my knowledge) :(
Sorry I didn't have better news