yep, it's all in Gminor.

Scales to play over the whole track:

Gminor Pentatonic
Gminor Blues
Gminor Dorian


You will have noticed that there is a sort of 'chorus' in the middle, which is still in G minor, but here are the chords for that:

Gminor/C7/Fmajor7//
Gminor/C7/Aminor/Dminor
repeat once.

I've posted up a quick sample solo on my purevolume so take a listen to that to get ideas, I'm using the Gminor Dorian and Pentatonic/blues for the whole song. I didn't do much in the chorus though...I'm sure you can go wild.

http://www.purevolume.com/julianvickers