megaupload doesnt support all countries. mine included. if it says that the slots are full, you may use the megaupload toolbar. the latest doesnt seemed to be a spyware.
an alternative, if u r using firefox, is to use an addon for megaupload available at mozilla site. or use google :)
although its not my preference (i prefer gigeshare), i dont have any problem so far in using megaupload. im a free member and can download 2 or 3 file a day even that my country is not supported
and if you dare walk the line, there are tricks in using it, just google around like gabrielshield said.