How large is windows vista home premium to windows 7 home premium upgrade?

[tiger c]

I want to upgrade from vista to windows 7.But I wanted to download the upgrade instead of using the upgrade cd instead of having to pay shipping.I Have a 256kbps dsl connection.Im currently using windows vista home premium X64.If anyone used this method could you plz tell me how large was the file and what was your connection speed? Thanks