Ah!!! Ok, I was thinking maybe the original might have been scratched thus causing the errors. well then just try it out and see if you can play it then. If your install was sucessfull then it should be ok. You mentioned it wasnt THAT scratched....Any scratches at all can be read as data and cause problems. You may be ok.
If it does skip or fail to work properly, try using an electric car buffer with a dab of car polish to resurface the disk, or tooth paste. If you dont have an electric car buffer, you can just use a cotton t-shirt. It will take alot of rubbing doing it by hand but eventually you will rub out the scratches. Then just re-install it again and see if that helps...as I said though, you may be ok as it is now...
