Sony will begin selling an after-market Blu-ray Disc drive next month that can be added to existing desktop computers. The BWU-100A drive supports burning to single- and dual-layer BD-R (single use) or BD-RE (rewritable) discs. A single-layer disc can store up to 25GB of data or about two hours of high-definition video, and the dual-layer disc can accommodate double these amounts. Sony will ship the drive with CyberLink’s BD Solution burning software. The drive can write at 2X Blu-ray Disc speed, so burning a full 25GB disc takes about 50 minutes, Sony said.