You can contact Microsoft about the SP1 problem, they have a free unlimited support. They maybe able to help, once you can get SP1 you may have an easier time with the other updates.
https://support.microsoft.com/oas/default.aspx?ln=en-us&x=8&y=7&prid=11274&gprid=500921
Although Dells recommendation of re-installing, maybe the way you want to go. Then right away before you install anything else (besides the os and drivers) you'll want to install SP1. Most people recommend installing SP1 as soon as you can, because Antiviruses and other programs can cause problems.