How can I use an arduino as an intermediary step between my PC and a LED strip?
You should take a look at FadeCandy if you are dealing with NeoPixel LED Strip. Ived used that in conjunction with Processing (which is JavaBased) to send stuff into a 16x16 NeoPixel display. (4 8x8 matrix's linked together) 
Fadecandy uses Open Pixel Control
http://openpixelcontrol.org/

I've got an example of it on youtube... https://www.youtube.com/watch?v=rz_U4dzjp1s&amp;feature=autoshare