There's a free iPad app that gives anyone access to a Windows 7 desktop and Microsoft Office 2010 from a tablet—but it's probably too good to be true. As we wrote on Thursday, Microsoft says the "OnLive Desktop" service that streams a cloud-hosted Windows installation to iPads and Android tablets isn't properly licensed. OnLive isn't commenting, but the company will probably have to re-work the service's structure, which has a free tier and optional fee-based upgrades, or risk having to shut it down.

That doesn't mean Microsoft's rules prohibit such services, but a properly licensed service is unlikely to be free. A company called Nivio explains how it plans to offer Windows and Office on the iPad and other devices while complying with Microsoft's licensing rules. To make it worthwhile for Nivio, the service will cost $5 for each ten-hour increment (only $2 for students).

Nivio hosts the service on Rackspace and pays Microsoft for a Service Provider License Agreement (SPLA) letting it deliver a "Windows 7-like experience" using Windows Server 2008 R2, which shares the same codebase, Nivio President Sachin Dev Duggal explained in a blog post on Thursday. Nivio delivers a cloud-based Office using Windows Server 2008 R2 and Remote Desktop Services, which can be done without breaking Microsoft's rules. To prove Nivio has the right agreement in place with Microsoft, Duggal pointed to a recent Nivio press release which includes a quote from a Microsoft spokesperson. (Press releases generally don't get issued with such partner quotes unless the service is a legitimate one.)

The Nivio service promises Windows access from "your Mac, PC, iPad, Android tablet or mobile device," or any HTML5-capable browser. iPhone and iPad support is "coming soon," the product page says. Whether that will come in the form of an app or browser access isn't specified. Interested users can pre-register for the beta, but there appears to be a waiting list. We registered last night, and received a message saying "We'll e-mail you as soon as your account is ready and waiting for you to use."