You can start over with the old disk and it's product ID code. But, if you can download the full SP file from MS which is about 320 megabytes, you can use "autostreamer" (look it up on Google) to make you an SP3 disk. You just need a burner and a program such as Nero that can burn iso disks. This will save you lots of update time but there will still be plenty more after that. Good luck.