I have lived here in Murfreesboro for all of my 31 years, and I have seen the schools grow and change, some for better, some for worse.
The previous posters are pretty accurate... Siegel and Blackman are considered better schools in M'boro. Let me just add to that and say that a school you DON'T want your child going to is Central Middle School. When I went there, it was the only middle school in M'boro, and it was fine. Now it's not the only school, and it has suffered for it. My cousin has taught English there for some years, but she is leaving soon because she just doesn't feel safe there.
Besides McFadden and Bellwood, you might also want to look into getting your younger son into Homer Pittard Campus School. While it is technically a public school, it is very much like a private school, but without the tuition. There is no zoning restriction, so you could live all the way across town and it wouldn't matter. It is affiliated with Middle Tenn. State University, and Campus School students enjoy many educational benefits as a result of that relationship. Enrollment is limited and subject to a waiting list. While children can be put on the waiting list for kindergarten as early as 3 years old, each grade has its own separate waiting list. I'm sure the waiting list for each grade is shorter as you reach each higher grade. It might be worth your while just to put your son on that list, because Campus School is far and away the best public school in Rutherford County, and probably in the state as well. The test scores are consistently unbelievably high. I went there, and I intend to put my child on the waiting list for kindergarten there. Also, the music teacher there recently won Tennessee Teacher of the Year honors.
As far as your husband working in Nashville, M'boro is very convenient to Nashville by interstate. I think you will find that M'boro is a wonderful place to live. Good luck!