first time video job

[Kofman13]

Ive been doing semi pro photography with my d90 for a year now as a side business. But i was contacted to record a concert and do post reception stills for a piano recital in a probably dim lit church.

my first idea: record video with d90 and 85mm 1.8 at 480p ( i think quality is decent plus i need the 20 min limit as opposed to 5 minutes because each piece will be more than 5 minutes long)

and planning to record audio seperately to my laptop with this mic and sync it later
B&H Photo Video Digital Cameras, Photography, Camcorders

ive used it to record my own audition cd on piano and it was pretty good.

is this a feasible idea?

also, what program should i use to record audio with? ( for my quick recording i used audacity LoL!)