A couple of suggestions to consider
1) So long as you have the license number you can still download a legal copy of Win7 for the license version you have from the Microsoft site. I did this last weekend for a machine I was setting up. This included SP1 and can be run from an external CD player (or with the correct formating software) from a flash drive. Just make sure your BIOS is set to allow you to boot from the device you are using.
2) Also if I recall correctly you can select how you treat updates - I think there is an option to download automatically which is best turned off to avoid the machine grabbing your Internet connection when you want to do something important on line.