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#21
SP1 is just a Service Pack, specifically the first (and currently only) one available for W7. These are merely a collection of security fixes and other OS patches that Microsoft have released since the original OS was made available. All current retail versions of W7 should already have this pre-integrated on the disk, so all you need to do is pop the disk in and install. If, by any chance, your disk doesn't already include SP1 (and I can't tell whether the Dixons one does or not), you can always download the appropriate standalone of SP1, burn it to a disk (or place on a USB stick) and then install it from that. If you have to go down that route, it is usually best to install the Service Pack immediately after installing W7, as that's the closest you can get to having it pre-integrated.
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