Two weeks ago, InfoWorld launched a petition campaign to save Windows XP. So far we’ve gotten more than 70,000 signatures, thanks to a passionate response from a wide range of XP users. We hope we can persuade Microsoft to keep selling XP licenses indefinitely, past the June 30 deadline, after which Microsoft has said no more shrink-wrapped or OEM licenses will be available for retailers, computer makers, and others to order. (Vendors can continue to sell by June 30 any XP licenses they ordered from Microsoft, but when they run out of those, they can't get more to sell.)

We fully acknowledge that, even if we get a million signatures, Microsoft may stick with its original plan. If new Windows XP licenses come to a screeching halt after June 30 as currently planned, what can IT do to get more XP seats? The answer depends on your licensing arrangement with Microsoft. The short answer for most users, though, is that Microsoft will let people with Vista Business or Ultimate "downgrade" to Windows XP Pro under specific circumstances.

Here, based on Microsoft's published documentation and on the company’s responses to our questions, is InfoWorld's guide to how you can get new XP licenses after Microsoft officially pulls the plug. Note that some of Microsoft's answers to us differ from what has been published on its Web site. Microsoft had changed some of its "downgrade" policies in summer 2007 and appears to have missed updating some of its documents.

Retail licenses
If you’re Joe XP user and you want additional upgrade or full-install packages, your only option is to stock up before the deadline. Only until July 1 can retailers order shrink-wrapped boxes of new XP licenses and upgrade licenses -- what Microsoft calls FPP (Full Package Product) licenses -- to sell to customers like you. Chances are these last licenses will sell out quickly after the June 30 order cutoff.

Also until July 1, individuals can buy XP licenses online from Microsoft (such as when you have an installation CD and need an extra license for it or when you need to load the software on a second computer), but not after that date.

OEM licenses
PC makers largely stopped selling XP preinstalled on new consumer-oriented desktops and laptops in spring 2007, although they remain available to business customers who order online or have a business account with OEMs such as Dell Computer or Hewlett-Packard. (Microsoft calls preinstalled copies of Windows "Direct OEM" licenses.) So larger businesses have by and large kept ordering XP-equipped PCs, although many individuals and small businesses bought Vista instead because they didn't know they had a choice. Recently, Dell began offering all customers, not just business ones, the option to get Windows XP instead of Vista on many models.

Today, people who have already bought Vista systems have two choices to get XP instead. One is to buy an FPP XP license before June 30 and install it over Vista.

The other is to "downgrade" to XP Professional, using an XP Pro install disc you already have or a "downgrade" XP Pro install disc supplied by the PC maker. Essentially, Microsoft lets you use your new Vista license for an XP Pro install. You have such "downgrade rights," however, only if you bought Vista Business or Vista Ultimate.

Note that you can't run both Vista and XP using the same license (so you can't, for example, install Vista on a virtual machine if you're also using the XP "downgrade" install as your boot OS). You get only one license and have to choose one OS or the other. And OEMs don't have to make the "downgrade" discs available to you.

Also note that any version of Windows preinstalled on a PC is licensed only for that computer and cannot be transferred to a different machine, so you cannot use such "old" licenses on new PCs, even if you no longer use the old hardware. But you can use your old XP discs under the "downgrade rights" conditions above.