OK mine took 3 DVDs for the Windows 7 alone and one for the actual Laptop Options separately..
Hence 4 DVD's..
If we go by what we discussed last night that's a grand total of 4 X 4.7 GB (single-sided, single-layer – common) ..
I think the 8 GB USB Drive might not do and certainly your two DVD's will not be enough if you go by what mine took for Windows 7 Home Premium Edition..
Ease wise the DVD-R's are better protection as once written they usually can be stored and are more easily used to boot up from.
That said, you do what you think best.. It's after all your decision..