there is an effective way, use speech synthesis softwares also called text-to-speech softwares. Most of the text-to-speech softwares can read text files in format of .txt and other file formats with natural voices using various voice engines. The text-to-speech voice engine on Vista is Microsoft Anna, and Microsoft Sam on the Windows XP. Vista users can hear a very clear voice of Anna in US English, XP users would think the voice of Microsoft Sam is poor, but they can get other company's US or UK English vocie engines which are more clear.
If your computer OS is English OS, you can install a speech synthesis freeware such as
Panopreter, It is an easy-to-use tool which reads files and converts files into wave and mp3 audio files, so you can listen to them with a MP3 player. Somehow, the speech synthesis softwares are educational tools, following the standard reading in US or UK English vocie, Your pronunciation will be improved.