Neo has a name. He had parents in the matrix so whatever they gave him will work. If not, just Neo will probably work. Was there a rule in the Death Note series that the only name that works is one given to you by your genetic parents?
Either, way I don't think Light can win this unless he does some serious planning and is made aware of the fight weeks in advance.
@battleheiz: Is there a rule in Death Note that says that only names given from genetic parents count? This would make adopted children and children with surrogate mothers immune to its abilities, which I don't think is the case. I'd lean toward a pseudonym being valid if you have no actual name more than leaning towards not having a name from genetic parents means you're invulnerable to the Death Note. Both of them don't have any real basic in cannon, but pseudonyms or given names seems to fit more with how the Death Note works than the invulnerability one.
Since the OP didn't define at all whats going on, I am to assume Neo and Light start relatively close to one another. If so, Neo Speed Blitzes him, knocking Kira's head off before he can open the notebook.
Maybe if you started him in some building with a few months of prep to find out who this Neo character is, get an image of him and a full name, hoping the Deathnote functions regardless of where it is, then maybe Light. But putting light against someone who will essentially eat him for breakfast isn't too fun.