I just got a Sony DRU-720A internal DVD+-RW/+-R/+R DL burner. WTF(ish) is the difference between + and -? Also, I could only find DL disks at CompUSA for $100 for a 25-spindle, so I won't be trying out that feature for a while. Are there any cheap/free progs to burn DVD/CDs with a Mac? The drive didn't come with any Mac software, and all I have is Toast Titanium 5.1.4. //edit: what burners are supported for iTunes burning? only superdrives? mine isn't supported.