Call it drinking the Kool-Aid, or just accepting business/IT reality — but more and more large enterprises are jumping on board the Microsoft/Novell agreement to provide support and interoperability between Windows and Linux.

While some open source industry watchers have been skeptical and critical of the Microsoft/Novell partnership, large firms such as AIG Technologies; Deutsche Bank AG; Credit Suisse; and Wal-Mart have signed on to the Microsoft/Novell technical support “ticket” scheme, where Microsoft says it will provide technical support for Novell SUSE Linux serves for three years. Technical aspects of the deal include the ability to run Windows servers as virtual machines on top of the Novell SUSE host, and vice versa. More controversial is the legal aspect of the deal, where Microsoft and Novell agreed not to bring any intellectual property suits against each other’s customers.

Most recently, HSBC, the London-based international banking giant, announced plans to standardize its data centers on Microsoft and SUSE, while using the Microsoft/Novell support plan to manage the changeover.

HSBC says it is using this program in its effort to change its various Linux and Unix platforms to a single version of Linux. (HSBC’s current environment is largely Red Hat-based, and also includes a wide Solaris deployment).

The Microsoft/Novell agreement will help HSBC “reduce the complexity of our Linux environment as we standardize our Linux infrastructure with SUSE Linux Enterprise and continue to extend the use of Microsoft Active Directory,” said Matthew O’Neill, group head of Distributed Systems for HSBC Global IT, in a statement.

Certainly, combined technical support, and virtualization interoperability will be useful in HSBC’s Linux/Windows deployment efforts. But you wonder how much of a factor the legal aspect of the Microsoft/Novell deal is shaping the IT decisions of HSBC, and other large enterprises using Windows and Linux.