Simplest way to transfer files from PC to Android device (wireless)
Airdroid can perform file transfers and it runs on 2.2 and above. 

All features:


SMS: send and receive individual or group messages.
Apps: Import and export .apk files.
Files: Manage files on Android and transferring files between Android and computer.
Photos: View and manage photos on Android and transferring photos between Android and computer.
Music &amp; Videos: Play and manage music &amp; videos on Android and transferring them between Android and computer.
Ringtones: Set music as ringtone and export any ringtone.
Contacts: View and edit all the contacts.
Screenshot: View the real time screen of Android devices, take static screenshots. (root required)
Camera: See through the lens of both front and back camera, also supports flashlight.
URL: Push url to Android and open automatically open it with Android browser.
Clipboard: Share clipboard content between Android and computer.