Companies shouldn't wait until Microsoft releases Windows 7 and skip Windows Vista altogether, Forrester Research wrote in a new report issued Wednesday. The fact that Forrester even had to put out such a report is just the latest sign companies are hesitant to upgrade to Microsoft's new operating system.

"Although we applaud companies for thinking ahead, there are some harsh realities for those considering skipping Windows Vista," Forrester analyst Benjamin Gray wrote. A recent Forrester report found that more than half of enterprises don't yet have plans for Windows Vista.

Forrester laid out several reasons that companies should move to Windows Vista soon instead of waiting for Windows 7. Windows XP, for example, will enter extended support later this year and is slated to become unavailable from hardware suppliers after June 30.

Meanwhile, the release schedule, features list and requirements of Windows 7 remain unclear. Microsoft has repeatedly said that Windows 7 will be available about three years after the general availability of Windows Vista, or sometime early in 2010. Current Windows chief Steven Sinofsky is known for shipping software on time, but Microsoft in general isn't, and Windows Vista's release slipped several times.

Contrary to widespread reports of difficult upgrades in the early goings that included major incompatibility hurdles, Forrester also argued that "the returns from early adopters have been impressive." The analyst firm pointed to better administrative tools, security tools like User Account Control, and Vista's integrated search functionality.

Forrester noted that while desktop operations managers are now coming around to Vista, CIOs remain reluctant, at least somewhat due to the negative press coverage it has received and also because of a lack of early adopter stories. "Because adoption has been cautious, it's been a challenge for companies to learn from early adopters," Gray wrote.

In a separate report also issued yesterday, Gray outlined tips from successful corporate upgrades to Vista. He recommended, as most companies already do, tying Windows upgrades to hardware upgrade cycles, pushing software vendors to ensure app compatibility, tweaking User Account Control to make sure it doesn't constantly annoy users with security prompts and resorting to virtualization as a workaround to pesky compatibility problems.

In that report, Gray noted that custom applications developed in-house are proving a significant compatibility stumbling block for many companies, but that can be avoided by altering apps to adjust to changes to administrative rights in Windows Vista, such as requiring rights to write to the Windows Registry.

This isn't the first time analysts have urged companies not to skip Vista. Last summer, Gartner also warned clients that they shouldn't necessarily skip Windows Vista, citing Microsoft's problems releasing products on time and a complete lack of details on Windows 7's features and requirements.