In the ultimate test to see whether or not Blu-ray is ready for mainstream adoption, Wal-Mart will be selling a Magnavox player for $128. If it creates stampedes like Wal-Mart’s $29 DVD player from 2003, we’ll know Blu-ray is here to stay. If people casually mosey over to the electronics department, glance at the tag, and head elsewhere, we’ll know that the high-definition downloading initiative is in full swing.