sharing programs, in my opninon kazaa is full of virus...

try use emule, shareaza, dc++... there exist a bunch of them just look for it in google.

for u download big files try use torrent programs

like
bitcomet / bitlord
shareaza (can downlaod torrent)
azerus
uTorrent

that for programs is the betters you can find but of course exist much more i hope this help u...