Splat
Very simple way to do it:
Opan Windows Sound recorder (Start - Progs- Accessories - Entertainment) then open your choice of wav.
Now go to Edit - Copy - Then either go to Edit paste or sit doing CTRL + V until you get to 1000 or whenever you get fed up.
When it comes to saving the file go to File - Save As then at the bottom of the save screen choose the Change format button and save it using something like MPeg Layer 3 ( I am open to suggestions as to other settings but for sheer size of file this works best for me) and also experiment with the Attributes which should be pretty self explanatory.
Now save the file.