Playing games without the disk

I have an XPS m1530 and can play all my games without the disk...I heard you needed to install some software to do this but I havn't done anything (at least on purpose). I can even play WC3 without the disk which especially surprised me because it is an older game (this probably has nothing to do with it but still...) I also can play all the Orange Box games and CoH. Is this normal? And if it is it seems a bit weird seeing how if I really wanted I could sell my games and still be able to play them.

There are a few games that require the disk still, like Halo, but you need the CD key for most games in-order to install them.roulettethedog

Nope, as of the most recent patch Halo no longer requires a disk :D