I bought this spindle of 25 Memorex DVD+R DL at Ebay, which were suppose to be 8.5 GB. I try to burn a 7.8 GB image and the software said not enough space. I went to properties at my computer and it said 6.5 GB total capacity. Am I doing something wrong? May it means that they are bad copies of the original? Is this normal for Memorex? If it is, is there a more thoughtful brand?