No .net is not needed for WPI. However it seems like you really borked your install somehow. Have you downloaded the full .net 3.5 and just gone ahead and installed it? (3.5 has all of .2, .3, .3.5 and all fixes for the 3...) The only real requirement for WPI is IE6 up to date. Not enough space to run WPI?? WPI isn't even configured to output that error.