PowerPivot Plugin For Excel 2010
The plugin for excel 2010 is available through Microsoft.
Follow THIS LINK
Included on that page is the x64 and x86 versions of the PowerPivot Plug-In for Excel 2010.
StartFragmentPowerPivot for Excel can be installed on a computer that has 32-bit or 64-bit Excel 2010. If you have installed the 32-bit version of Excel, you must install the 32-bit version of PowerPivot for Excel. Likewise, if you have installed the 64-bit version of Excel, you must install the 64-bit version of PowerPivot for Excel.EndFragment