Matt Loney: Take the PCs away from your users and it can add up to a particularly elegant solution that even HP is now beginning to cater for

There is a mathematical expression often discussed in certain pub landlord circles that if you add cockneys to a place, then you get a fight. From this it follows that if you subtract cockneys from a fight, you just get a place. Its not quite clear what happens if you remove the place from a fight -- presumably you're left with a bunch of cockneys floating around nowhere in particular flailing their arms --- but you get the idea.

I'm sure there must be a similar equation that works for users and PCs. Take a user, add a PC, and you get a support call. Or a cup full of cappuccino in the CD-tray. Or in some cases -- and I think we'd best leave the logic behind this one to the likes of Bertrand Russell -- you end up with no PC at all.

There is a solution to this, and that is to remove the PC from the user in just the same way that pub landlords remove the cockneys from the fight. I'm not going to consider what happens when you rearrange the equation to get a support call minus a PC, but what is clear is that a user minus a PC can be a very neat result to a lot of problems that plague IT departments everywhere.

The solution is called a blade desktop, or a blade PC. Blades, for those not continually grinding away at the bleeding edge of IT, is the term coined for computers fully contained on a single board (blade) that fits alongside a dozen or more similar computers inside a cabinet that sits in a rack. A connector at the back of the cabinet links all the blade computers together and allows them to share such essentials as power and in some cases storage, and makes it easy to manage them from a single console.

Last year, server vendors got very excited about blade servers because they are something new to vend. Analysts got very excited about blade servers because they are something new to analyse. And right now IT managers around the country are cutting their teeth on blade servers, but we have yet to see evidence that they are getting quite as excited as the vendors and analysts (a familiar story, that).

Blade desktops work on the same premise as blade servers -- that of a rack-mounted cabinet containing a dozen or so computers. But in this case the blades are set up with desktop software, and the cabinet requires some smart switching at the back and some long cables to transmit video signals to monitors on the users' desktops and to transmit mouse and keyboard signals back to the cabinet.

This year it looks as though blade desktops might be gaining more cachet, thanks mainly to HP -- the biggest PC maker in the world -- joining such stalwarts as ClearCube in producing the things.

If anything, the blade desktop makes a whole lot more sense than the blade server. For a start, they allow you to physically remove the PC from the user; all they are left with is a screen, a keyboard and mouse, and potentially extras like USB cables. That means less chance of the PC getting damaged or even stolen, and you get to pull users' data back into the server room without them feeling they are losing control over it (how much sensitive data is stored unencrypted on users' hard drives?).

But the benefits go way beyond that. Having all the PCs locked away next to each other in a server room means that it becomes possible to use empty space on the hard disk of one PC to back up data from another. It means that, with the right switching gear at the back of the cabinet, you can begin to treat the workstation more like a telephone so that the link to a particular PC can follow a user round the office from desk to desk, much as a telephone extension can be reallocated. And it means power consumption can drop by as much as half, while backup power can be more easily provided: consider the ease of buying a single UPS for a single rack of blades compared to the hassle of putting a UPS under every desk in the company.

Naturally, there is an issue over how far the blade can be removed from the user, and this limit is dictated by the cabling used. ClearCube reckons it can manage 200 metres with an analogue signal over Cat-5 cable, which should be large enough for most offices. HP will have to match that, and could even win a few points if it is able to tweak its OpenView management suite sufficiently to support the blade desktops. But the proof of the solution is in whether the numbers work, and they do: IDC estimates that blade desktops can result in a 30 reduction in support costs, while bringing availability up to 99.9 percent.

Remote desktop setups (few have so far involved blades) have to date largely been the preserve of city trading floors, where space is scarce and where hundreds of PCs would quickly raise temperatures. The move by big PC makers such as HP into the market can only help lower prices and make the technology more accessible, and that adds up to more users with less PCs to break, and that should be a good result for everyone.