Click View then enable Equalizer
Then make sure You have the button set to on and adjust the bar shown here
Alternatively download Audacity
http://audacity.sourceforge.net/download/windows
Make sure you install the LAME MP3 Encoder otherwise you wont be able to convert the files to MP3 in Audacity you can highlight the whole track and amplify it as much as you want (Just don't increase it to the point where static starts occurring). Modifying this affects the track so its increased volume no matter what music program you use.
Threaded Mode