можно еще и вот так))

void loader_nam()
{
QEventLoop loop;
QNetworkAccessManager manager;
QNetworkReply *reply = manager.get( QNetworkRequest( QUrl( "http://prog.org.ru/Themes/default/images/smflogo.gif" ) ) );
QObject::connect( reply, SIGNAL( finished() ), &loop, SLOT( quit() ) );
loop.exec();

qDebug() << reply->error() << reply->bytesAvailable();
QByteArray buf = reply->readAll();
QFile file( "save.gif" );
if( file.open( QIODevice::WriteOnly ) )
{
file.write( buf );
}
}