[DABhand]

its 10.4mb on mine.

which is roughly the same as yours, depending on your OS etc.

If your worried you could download the steam installer from valve, and copy the contents of the DVD to a temp folder and replace the DVD steam files with the ones you downloaded (or the ones on the HL2 DVD).

And burn the disc, that way it should install without a problem.

But remember, if you have this game under 2 weeks, I think the law applies in Oz that you can return the game to place of purchase and request new media. Look into that cause if they refuse you without a good reason they are breaking the law then.