1. A method performed by a virtual process manager and a client application both executing on a first computing device, the method comprising: the client application connecting to a second computing device over a network, the second computing device storing a virtualized application file at least partially implementing a virtual application, the second computing device transferring a webpage to the client application, the webpage identifying the virtualized application file as being available for download, the webpage being operable to receive, from a user, a user command to execute the virtual application at least partially implemented by the virtualized application file; the client application receiving the webpage; without user input and before the webpage receives the user command to execute the virtual application at least partially implemented by the virtualized application file, the client application sending a command to the virtual process manager to download a portion of the virtualized application file from the second computing device; without user input, the virtual process manager downloading the portion of the virtualized application file from the second computing device, and waiting to execute the virtual application at least partially implemented by the virtualized application file on the first computing device until the virtual process manager receives a command from the client application to do so; after the virtual process manager has begun downloading the portion of the virtualized application file from the second computing device, the webpage receiving the user command to execute the virtual application at least partially implemented by the virtualized application file; after the webpage receives the user command to execute the virtual application at least partially implemented by the virtualized application file, the client application, sending a command to the virtual process manager to execute the virtual application at least partially implemented by the virtualized application file on the first computing device; and in response to the command to execute the virtual application, the virtual process manager downloading any portions of the virtualized application file not previously downloaded from the second computing device, and executing the virtual application at least partially implemented by the downloaded virtualized application file on the first computing, wherein the virtual process manager does not query the user for any information during the download or execution of the virtualized application file.