I used ES File Explorer for sideloading I just made a folder in root that I move the apk's over to while connected to computer. If the only thing you are going to use ES for is to sideload it's nice that it can remember your last open folder - every time you come back to it it's open to your folder.
I also used a combo of programs to stream avi files from my all win7 home network to the fire. I sideloaded moboplayer and configured it to software-decoding. Then I got, from the fire marketplace, skifta. Those two in conjunction allow me to watch the shared media from my home network. very nice