YOU can use your Windows 7 Upgrade disk to do a clean install WITHOUT having the old OS on it.
ADDED: PS this is ONLY legal if you own the qualifing uprage OS - WHICH YOU DO!
I Recomend the Clean install when going from a HDD to a SSD unless there is a good reason not to.
To use Windows 7 Upgrade to do a clean install can just google (will add steps in a min)
1) as already stated. !) disconnect all hdd so that only the SSD is connected. 2) make sure Bios is set to AHCI.
2) Place Windows 7 Upgrade disk, boot to it.
3) select Custom Instal, Do NOT input your key when prompted.
Method 1). Once windows is installed, reboot to dvd and this time select Upgrade and imput your Key this time.
Method 2, which I PREFER):
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A true geek has never been intimidated by the registry, but lets face it, it's a mess in there. To access the registry you will first need to open up the start menu and type "regedit" into the search field, followed by enter. To find the proverbial needle in this haystack, you will need to navigate through the tabs listed on the left in the following order:
HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/ . If you don't like doing it the hard way just click Edit then Find and type MediaBootInstall into the search field, and press enter.
Once found, double click MediaBootInstall and change the "1" to a "0". Once you have finished this, simply click Ok and close out the Registry Editor.
THEN
Before we try to activate our copy of Windows, we need to reset or "Re-Arm" the activation sequence. To do this, simply open up the start menu and type cmd but instead of just pressing enter, you need to press "Ctrl" + "Shift" + "Enter" to run it as an administrator. You can also accomplish this by clicking the start menu, typing cmd into the search box, then right clicking the command prompt application and selecting Run as administrator.
Once the command prompt appears type slmgr /rearm and press enter. Next simply type Exit and hit enter again, after which it will ask you to restart your machine.
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Source:
http://www.maximumpc.com/article/howtos/how_use_your_windows_7_upgrade_disk_fresh_pc?page=0,1