Fortunately, with the help of Android Data Manage tool, you can import your messages in .xml format from computer to your device or export text messages from device to computer as .xml or .txt files easily.Take a trail version of Android Data Manage to transfer your SMS to computer.
Install the program on your PC first. Then, launch it and bring yourself to the primary window. Connect your Android phone to computer via a USB cable. Once Android phone is connected, the program will detect them automatically and shown up the window as below.
Note: Android Transfer is fully compatible with all popular Android phones like Samsung/HTC/Google/Motorola/Sony Ericsson.
Click on the SMS tab to enter the SMS management window. All your text messages will be list in front of the SMS management window as below. You can choose those messages you wanted and then click the "Import/Export" button to save them on your computer in .txt format.
Now, download this program to have a try!