volume size doesn't match what "Get Info" tells me

[annagrimm]

I just got a new Macbook Pro, and I transferred a bunch of my stuff over from an old mac, and now it's saying my startup disk (140gigs) is full, with just under 2mb space left. So I ran disk inventory, and it says I've only used up 70gigs. I'm thinking that right-clicking on my hard drive on the desktop is giving me the correct amount, but how do I see where these lost 70 gigs are?