Photoshop? Wilson is the perfect place (Av. Garcilazo de la Vega, behind Sheraton Hotel).

Gamarra Market is not so safe, beware. Besides you'll find so many different places that it would be difficult to buy. Try "La Quinta" or some other similar stores, they sell brand name stuff for extremely cheap prices; although it might not be as cheap as Gamarra, there's no need to take a taxi for a long distance place and no risk of pick pocketing. They are in Jr. De La Unión (Downtown) and LArco Avenue (5th block) in Miraflores.

Virus free.. it would be the only thing in Peru that was. You are taking a risk on software that is pirated unless it is Mac software. You want quality stolen software then buy it from the Russians.

When I was on the bus from Lima to Ayacucho, after awhile, the movie started stalling and eventually crashed. Perhaps the DVD was pirated? Av Wilson/Garcilazo de la Vega is a strange scene. People on the sidewalk hawking software CD's in plastic sleeves...