last year my mac stopped working but as it was still covered by the warranty i got it repaired. however, it was repaired by an Apple Service Provider, not Apple themselves, as i live in Spain and there isn't an Apple shop here.

when they fixed it they wiped pretty much everything off it, including a lot of the free applications, most notably Garageband. i still have my install discs but disc 1 is badly scratched and doesn't seem to work any more.

my question is, can i use my sister's install discs to reinstall garageband? is it possible and if so it is legal?