I have that same exact drive, or somelike very close to it...... Its great
Anyways the difference between the two is
the - format was developed by Pioneer. Based on CD-RW technology, it uses the same "burn" technology as CD-R's, this format is standerized by the Intl DVD forum. DVD - has better DVD playback compatiblity within home DVD players
the + is also based on CD-R technology. DVD+R/RW is supported by Sony, Philips, HP, Dell, Richo, yamaha, and others, DVD+R/RW is not supported by the international DVD Forum, but the Forum has no power to set industry standards, so it becomes a market driven issue.
DVD+ has faster speeds and higher sustained transfer rates.