Please help me to correct the following sentence

I have never heard or read the word upgradation.  My online dictionary does list it, but my spell checker doesn’t recognize it.  The more common term is simply upgrade.

I really have no idea what “Microsoft upgradation PC details” means.  It is confusing and vague.  Perhaps you are giving details about some software that will be upgraded on that date.  On the other hand, maybe the recipient has been instructed to upgrade his computer hardware and you are providing details of what is required by that date.  Either way, be more specific so it is clear.  What are the details about, the software or the hardware?  Do you want the person to just find the details or do they need to do something else?

PC originally was an abbreviation for personal computer, but it is now a generic term for a computer that runs on a Microsoft operating system.  If you are already referring to Microsoft, I would probably just say computer rather than PC because it sounds more formal. 

Both your sentence and Sanjay’s suggestion state that the details (not the upgrade) are scheduled for a certain date.  You need to rearrange the sentence so the reader knows what is scheduled.   You might need to make this into two sentence to add some clarity.

The Microsoft Windows 7 upgrade is scheduled for August 23, 2012.  Please follow the instructions in the enclosed details to prepare your computer.  

Please find the Microsoft upgradation PC details scheduled for  August 13, 2012.