Altiris has released its Windows software virtualisation system SVS, offering it free for personal use. Like rival application virtualisers such as Softricity, SVS allows applications to run in a sandbox, isolated from the operating system.

It works by acting as an application wrapper, so you don't install to Windows, you install to an SVS 'layer' then run from that. This layer holds all the relevant registry settings, DLLs and so on, communicating with a filter driver on the operating system. A sublayer for data holds the application's user settings. Layers can be created for Windows patches too.

This all means you can do otherwise impossible things, such as run Microsoft Office 2000 and 2003 on the same PC simultaneously. It also keeps the operating system clean, so badly behaved applications don't conflict with it or each other - the 'DLL hell' familiar to PC support techs - and it allows an application installation to be fully reversed if it causes problems.

SVS, which Altiris acquired with a company called FS Logic, also integrates with Altiris' provisioning tools, allowing applications to be deployed as virtual packages. It launches as SVS v2 - v1 was the unreleased FS Logic technology - and the company already has a technical forum for SVS users running.

"It's a new way of thinking how you're going to manage your infrastructure," said Altiris EMEA general manager Ed Reilly. He added that for commercial use, SVS would cost just £18 a seat.

However, David Greshler, Softricity's co-founder and VP, pointed out that SVS still installs an application to a specific PC, even if it is then insulated from the operating system. "If you go to a new location, you have to wait for the application to be pushed out again," he said.

He added while Softricity costs $200 (£114) a seat, it includes deployment software which enables applications and user settings to be dynamically streamed to a user whichever PC they're using, in effect creating a virtual desktop.

"Their deployment software is an extra $100," he said. "What they've done is a great fix for the old way of getting applications out to people. But assigning hardware to specific users is a very old fashioned way of doing things."

Altiris systems engineer Marco Heineck said that it is possible to put SVS layers on a network share. He stressed the value of SVS in conflict management and software migration, adding: "We wanted it to be desktop or server specific.

"Yes, the layers are machine-dependent - we are not trying to reinvent what the operating system does. But you can mix in VMware and run it in a virtual environment too."

Reilly said that Altiris has a partnership with VMware. The two are complementary, he said, as they address different parts of the virtualisation puzzle - software insulation vs hardware consolidation. He added that Altiris partner Dell has already signed up to both sell SVS and use it internally.