Samsung Electronics and Hewlett-Packard Co. are dropping new entries into the tablet computer market in an efffort to bite into Apple Inc.'s (Nasdaq: AAPL) huge chunk of the tablet pie. The Wall Street Journal reported that on the eve of Monday's Mobile World Congress opening in Barcelona, Spain, Samsung announced that it has launched its new 8-inch tablet called the Galaxy Note 8. It will go on sale in the second quarter and will be powered by Google's (Nasdaq: GOOG) Android system. The new tablet…