If the resonant frequency is above 100 Hz, then why are you using an accelerometer rather than a microphone? A microphone feeding a sound card can easily be captured as a .wav file, which immediately gives you the option of seeing the waveform as a graph using something like Audacity or Goldwave.

For analysis in Excel, you would again need to find a program to translate the .wav file's binary words to another format, as discussed above, bypassing whatever words are file header rather than data. (In fact, Excel will store the words' values internally as binary numbers, but as a different kind of binary numbers -- floating point -- than the kind of binary numbers in the .wav file.) One approach would be to use an Excel VBA program to read the file words and populate the spreadsheet with their values. Although such a program would not be very large, it would not be a good starting project for someone who's never used VBA and who's new to the idea of binary-coded numbers. However, outsourcing the writing of this short program might be a reasonable strategy, if there's nothing suitable already out on the 'net.