video editing software

hello everyone.
i would like to edit some riding videos ive made but the sound is crap. Resonating engine noise is just awful. I want to replace the audio with mp3 music. What software are people using to cut and dub out the sound?

Im currently using the old Drift HD720 camera.
Most interesting position ive found is mounted either on the clutch cover or the stator cover. Gives some great angle shots especially when you have got a bit of a lean into a corner. The road gets pretty close!
Cheers!

FCPX if you're on a Mac.
I just posted a multi cam (3) clip today to YouTube. I trying to get the hang on a Zoom H1 as an audio recorder. Still working on that.
YT doesn't like you using copyright material and blocks videos from playing on some phones/tablets.
GoPro has some pretty good software but I've never used it.