We're all for converged devices in the Digital Home corner of TechRadar. But the recent arrival of the Silicon Mountain's Allio shouldn't inspire a mad rush to buy into an all-in-one home entertainment system.

It's a question of quality. The problem with converged devices is that, while they successfully combine several different devices together, some of the core functionality tends to suffer. You just can't fit everything in and keep the price down.

The Allio is an engineering success, but consider what you get for your money. The top-of-the-range 42-inch Allio is priced at $2,799.99 (£1,813.69). Spend this and you'll get a convenient combination of a 1080p LCD and a Intel Core 2 Duo-powered PC (with 2x Blu-ray drive). And all in one tidy (and apparently wall-mountable) unit.

But the devil's in the detail. The Allio is less a TV with a built in PC, than a PC with an extra-large high-resolution monitor. The TV part only has two HDMI ports and a pitiful 2,000:1 contrast ratio. The PC might have 1TB of storage and 4GB of RAM, but the integrated Intel GMA X4500HD graphics card is going to struggle with Far Cry 2 and Fallout 3.

As an alternative, you could buy a Philips 42PFL7603D 1080p TV, which boasts a 30,000:1 contrast ratio, four HDMI connections, PixelPlus 3 HD picture processing and love it/hate it Ambilight. At the time of writing it costs around £800.

Pick up a PlayStation 3 for Blu-ray and DVD playback (£289) and that leaves £724 and some change to invest in a new PC.

We've seen the likes of the Allio before in the short-lived eXentia and Lumina PCTV models from Elonex. The criticism was the same. It's easier to buy better-specced, separate components than get suckered into a digital home experience that looks the part, but won't live up to expectations.