There's a small firmware update for the D5000:
Distortion control data upgrade for D90 and D5000
Instructions: http://nikonimglib.com/dcdata/manual/En/lensprofile_win_en_ABF.html
Distortion control data upgrade for D90 and D5000
Instructions: http://nikonimglib.com/dcdata/manual/En/lensprofile_win_en_ABF.html