With a combination of file-system filtering and multilayered, local caching of code and data, SVS intercepts application calls made to the Windows file system (including calls to the registry hive files) and redirects them to a private, hidden cache file. This redirection lets users install an application without modifying the PC's configuration. All changes that the installation program would make are isolated from the actual runtime environment.

Although the concept of application provisioning isn't new, "Altiris validated the technology [with SVS] and priced it at a point where it's set to become a mainstream technology," says Mike Silver, an analyst at Gartner Inc.

Application provisioning has universal benefits. "A 10,000-user company could have 1,000 applications. Figuring out what the interaction is between those applications ... is difficult, if not nearly impossible," Silver says. "So allowing applications to run in their own virtual space reduces the amount of cross-application testing ... and lets you better manage your desktops."

Cook hatched the idea for SVS back in 1998. "I was trying to think about how we could uninstall software 100 percent all the time," says the SVS architect. He sought the help of a formerNovell Inc.colleague, Jared Blaser, who he knew would have the knowledge and contacts to get his idea off the ground. Together they formed a company in 2002 and, with private funding, began developing SVS in Cook's basement.

They toiled for two years. "The hardest part was probably doing the registry virtualization, because there is no documentation on the registry at that level," Cook says. One of his first "eureka" moments was while trying to virtualizeAdobeAcrobat Reader and Quicken applications. "The first time we saw icons blinking on and blinking off, we knew we had something going," says Cook.