Sorry, IBM (NYSE:IBM). Tough luck, Hewlett-Packard (NYSE:HPQ). Dig deeper, Dell (NASDAQ:DELL). Servers -- once considered the Big Engines of a web-driven economy -- are the least attractive option for technology investors, according to analysts at Credit Suisse.

Everyone wants a Prius, even in IT
More specifically, Credit Suisse says that tech buyers will spend more on blade servers, as the sort of Big Engines that made Sun Microsystems (NASDAQ:JAVA) rich in the '90s lose their luster.

"We believe blade servers will be the most strategic segment for vendors," reads a research report excerpted in Barron's. "We believe blades will represent the key source of industry profit and revenue growth in coming years. Our forecast suggests that blade servers will account for 21.3% of server revenue in 2012, up from 10.3% in 2008."

There are good reasons to trust Credit Suisse's numbers. But before I get into why, you may want a little background about blade servers. Picture your PC's innards -- the green "motherboard" that has a bunch of chips glued to it -- and you'll have a rudimentary idea of what a blade server looks like. Essentially, it's a naked server, a chip-heavy slab of pure processing horsepower that slides into a cabinet, where it is cooled by fans and connected to data-storage devices.

Stripped-down servers are cheaper to buy and arguably cheaper to maintain. They don't have as much "stuff," and they can be swapped out when needed, like an oil filter for your car. IT managers love this. Server makers love it less, because there isn't as much profit to be had in the blade business. (On the flip side, they may also sell more blade servers than Big Engines -- potentially great news for commodity specialists such as Dell.)

More broadly, the shift to blades suggests a broader trend towards common, lower-cost systems and open-source technology. Big Engine makers like IBM are adjusting by pitching whole packages of servers, software, and professional services.

Who needs an operating system?
Others, like Oracle (NASDAQ:ORCL), are adjusting by concentrating on specialist hardware devices known as "appliances." CEO Larry Ellison waxed enthusiastic about his company's try at a database appliance called Exadata during this week's earnings conference call.

Exadata, built in concert with HP, is winning customers from Teradata (NYSE:TDC), IBM, and others, Ellison said, because its highly tuned combination of hardware and software vastly outperform Big Engines that run databases and a mess of other stuff. Specialization breeds performance, according to Oracle.

What's more, Big Engines are like PCs, in that they depend on operating systems. Some run versions of Windows, others Solaris, and still others Red Hat's (NYSE:RHT) particular blend of Linux. Ellison envisions future appliances like Exadata not needing a server OS.

"We have the Oracle database running directly on a [virtual machine] with no intermediate operating system, so that's actually up and running," Ellison said during the earnings call.

Think about that, and then think about a recent announcement from the Norwegian browser maker, Opera. Its new service, which it calls Unite, is designed to transform average PCs into -- wait for it -- servers.

"We are giving developers a chance to develop applications (known as Opera Unite services) that directly link people's personal computers together, so that you can connect with one or more of your friends at the same time. It all happens through the browser, so no additional software has to be downloaded," wrote Opera's Lawrence Eng in a recent blog post.

No wonder Sun fell into Oracle's waiting arms. Big Engines, its bread and butter, are beginning to look irrelevant even on the Web.

The future isn't served
All the same, investors shouldn't panic. All of the remaining server suppliers are fairly well-diversified, and those who businesses are built around data centers that serve content -- Akamai, for example -- are as important as ever. Server usurpers such as Opera Unite are still very early in their development.

But they're here, they're aggressive, and they want their pound of plastic. Be vigilant, tech investors. This is a war worth watching.

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Fool contributor Tim Beyers owned shares of IBM and Oracle at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Twitter as @milehighfool. The Motley Fool is also on Twitter as @TheMotleyFool. Its disclosure policy serves fresh disclosure-y goodness daily.