Hi Albatross72,
It is perfectly OK to copy your game onto a DVD. In fact, it is to be recommended.
Once you have the game on disc, if any thing happens to your computer, for example if it crashes,
your game is safe and can be re-loaded when all is well.
By the way, if you bought the download version of SS2008 then you should be able to re-download it from the Vstep website if you go into "My account".
Regards,
Angus.