Burned Vice City but it won't play

[Markme123]

A friend of my cousin's bought the PC version of GTA Vice City. I proceeds to burn the game onto 2 blank CDs for my cousin and me (You need to have disc 2 in the drive while playing).
I am borrowing the burned version right now and installed it onto my computer. After installing everthing I clicked on the game shortcut on my desktop. Although I have disc 2 in, it keeps on telling me to insert the CD. My cousin said it was because the programers did that on purpose incase people burn the CD and try to play it without the original CDs.
He said that we would have to "overwirite" it or something and proceeded to add ".bak" to the end of it along with doing some other stuff (folder options?). It was pretty quick and looked simple. I then clicked on the shortcut again and it worked.
For whatever reason I had to uninstall and need to do this all over again. Can anyone help me or give me directions? Thanks.

[TippeX]

buy a copy for yourself.. read the rules next time before you post