The installation clocks in around 530MB, and you can choose to install it via a Windows Update or by grabbing an ISO file which you can burn to CD.
On the other hand, you don't need to bother. Signaling a significant change in strategy, the last few service packs for Windows have essentially been a roll-up of existing updates, and contained no new features or functionality. Windows 7 SP1 is no different, so if you're already fully patched, there's nothing here for you. You can wait for SP1 to be officially released and get it through Windows Updates.