A certain truth about the big IT vendors is they want to sell as much as possible to any one customer and now, with virtualization, cloud computing and very tight IT budgets, they believe they have an opening.

There are effectively four enterprise vendors today: IBM, HP, Oracle-Sun Microsystems (which are due to merge), and now arguably Cisco Systems, EMC and VMware, which this week announced plans to jointly offer what they called a "Virtual Computing Environment" that will be supported through a joint venture called Acadia .

Analysts said Acadia is as good as anything arriving out of a merger. These mergers and joint agreements are giving the enterprise vendors the means to sell complete data center infrastructure environments.

Oracle's acquisition of Sun, announced in April and approved by the DOJ in August , gives Oracle hardware capability. As well as teaming up with EMC, Cisco announced its decision in June to begin offering its own server hardware .

HP's acquisition of EDS , completed one year ago, boosted its services capability considerably. IBM has always had the ability to offer complete systems and services from the days when the mainframe was the data center.

On Wednesday, HP sketched out its approach to data centers, its "converged infrastructure," that combines existing technologies and some new ones, including an updated Neoview enterprise data warehousing platform, into one single offering.

HP believes that the best way for enterprises to strip costs out of the environments and free up IT dollars for other uses is to integrate, standardize and virtualize as much as possible. They couple that capability with business intelligence and warehousing systems built on its Neoview system that runs on its Integrity BladeSystems, as well as improve cross platform integration with its Unix systems.

It has virtualized I/0 and storage, and can manage environmental systems through its smart grid technology that can tune infrastructure demands, power and cooling, to application loads.

Charles King, an analyst at Pund-IT in Hayward, Calif., said that "there seems to be a move afoot to enable enterprises and service providers to exert the kind of highly integrated and optimize management of their data centers that in the old days that were able to exert across a mainframe system."

HP CEO Mark Hurd told users at Gartner Symposium/ITxpo last month that he didn't want to compete with other vendors on point solutions, but instead wanted to provide the entire stack. Part of that effort has been through acquisitions.

One example is the scale out storage technology HP acquired through its acquisition this summer of IBRIX, a privately held company in Billerica, Mass. Its technology has been integrated in HP s converged offerings.

As HP and the big vendors generally expand the ability to offer broader range, by HP and others will be up against enterprise customers wary of lock-in.

Gordon Haff, an analyst at Illuminata Inc., said where competitive advantage for users matters the most is in the applications, not the infrastructure. "[Vendors will argue that] you don't get competitive advantage from bits and pieces of an infrastructure, you get competitive advantage from an entire infrastructure that is running smoothly," he said.

HP is betting that users will invest in new technology, in part because of what it learned by interviewing more than 400 CIOs worldwide. In that survey, more than 70% of the respondents said that they would sanction more IT investment if it was improving time to market and creating opportunities.

Deborah Nelson, senior vice president marketing of HP Enterprise Business, said they customers believes that the market will be unpredictable for several years and that is driving customers to seek improved insight, as well improvements in the ability to drive revenue.