No one really gives a damn when a new PC manufacturer enters the market selling its own-branded Windows computer. The launches of Wizard Micro, Delta Desktops and Lasco laptops do not set the web’s blogs alight.

They’re just another bunch of plastic/metal boxes running standard components, initially put together by a small bunch of grunts under some railway arches. It will be cheap – probably so cheap that the company will go bust as soon as it tries to market itself.

But it’s a very different matter when there’s a new company making and selling Macs, and – after 11 years without anyone but Apple in the market – there’s a new player in town; although possibly not by the time you’re reading this…

Psystar - based in Miami - claims its new computer will run Mac OS X 10.5 Leopard. It even calls its Open Computer “The Smart Alternative to an Apple”.

“Why spend $1,999 to get the least expensive Apple computer with a decent video card when you can pay less than a fourth of that for an equivalent sleek and small form-factor desktop with the same hardware,” boasts Psystar.

The basic configuration of the Open Computer costs just US$399 for 2.2GHz Intel Core 2 Duo processor, 2GB of RAM, 20x DVD writer and 250GB hard drive. That price doesn’t include Leopard itself, Wi-Fi, or even a mouse and keyboard. Add these and the price rises to $740. Oh, and no iLife – add that and the price goes up again to $820.

(Sorry for all the US$ prices but the Open Computer isn’t available in the UK, and I really doubt it ever will be.)

Apple’s cheapest desktop is the diminutive Mac mini, which comes with a 1.83GHz Intel Core 2 Duo, 1GB memory, and a 80GB hard drive – at a price of $599, plus $98 for keyboard and mouse, so more like $700.

While the Mac mini is $120 cheaper than the Open Computer, its technical specs are lower. The processor is a little slower, but probably not enough to worry most low-end users. Having only half the memory will certainly make a difference, and Apple would charge you $100 more to reach the 2GB offered by Psystar, taking the configured mini to nearly $800 – very close to the price of the Open Computer. The hard drive is three times the size of the Mac mini’s, and in a world of 160GB iPods, an 80GB disk is rather lame.

(We tested the Open Computer and found the Psystar to be 28 percent faster than the high-end Mac mini and 8 per cent slower than the low end iMac.)

But the key to the real appeal of the Open Computer is its extensibility. Unlike the Mac mini it can be configured with an optional fully fledged 256MB nVidia GeForce 8600 video card for improved graphics performance and “drastically improved performance in gaming”. Oh, and you can get it in Black/Silver, Black or White.

Windows PCs have always been popular with gamers and geeks who like to be able to modify (or “mod” if you want the whole exercise to appear cool) their computers to gain that extra ounce of power they need to play the latest graphics-heavy entertainment titles, or just make their machines look bangin’, with flashing lights and go-faster stripes. With an Apple computer all you can do is whack on the white Apple logo sticker.

Psystar is effectively offering to fill the yawning gap in Apple’s Mac line-up – for a mid-level upgradeable computer that offers more than the Mac mini but is cheaper and more adaptable than the iMac (iMac prices start at $1,300 for a model with 2GB RAM, but also a rather nice 20-inch display, don’t forget).

I don’t expect many diehard Mac users to be queuing up to buy the Open Computer, but it’s not aimed at people wanting to upgrade their old G4s and G5s. Psystar has its eyes on a much larger market – one that Apple itself is rather keen to get its hands on: disgruntled or curious Windows switchers.

These guys don’t care that the Open Computer is ugly and will clash with a third-party keyboard and mouse. But they are very price conscious, and may be reluctant to pay a premium for aesthetics. (Yes, Mac prices are more in line with Windows PCs these days, but, as the above example proves, this can be at a compromise of power and storage.)

Psystar also offers an OpenPro Computer, which is better looking (as far as I can tell from the company’s shiny pictures) and starts at $1,425 with keyboard/mouse, Wi-Fi, Leopard and iLife included. Apple’s Mac Pro is much more powerful but prices start at $2,799. This is possibly attractive where a Mac user who doesn’t want the (albeit attractive) limitations of the iMac but can’t afford the giant jump to the Mac Pro.

Finding buyers for its computer is probably the least of Psystar’s problems. Apple’s end user licence agreement for Mac OS X states that “You agree not to install, use or run the Apple Software on any non-Apple-labelled computer, or to enable others to do so.” And Apple’s lawyers like to shake about the bloody remnants of their victims after gorging on their entrails. And, as the company has shown with its attacks on iPhone hackers, it can disable non-Apple hacks with a simple free software download. Mac OS X 10.5.3 could quite easily “brick” Psystar’s systems.

Back in 1995 Apple did grudgingly and belatedly allow certain manufacturers to sell their own Macs. Power Computing was the most popular (and fun), and there were others such as Motorola, Radius, DayStar, and Umax. UK reseller Computer Warehouse produced a range named after cities, and even played around with different colours – years before Apple unveiled the iMac (itself dreamed up by a toilet designer from Chingford).

But after cruelly bringing down his axe on the Newton MessagePad newly returned Apple honcho Steve Jobs swiftly chopped the Mac clone project – significantly before the launch of the iMac and delayed release of OS X. The cloners merely took buyers from Apple rather than growing the market, leaving Apple with the R&D bill and fewer customers.

So if Apple is likely to pounce on Psystar, strangling its cheaper Leopard computers at birth, what are the guys in Miami thinking about? I hate to be a cynic, but maybe all the publicity will attract the Linux and Windows customers who can also install their favoured operating systems on the Open Computer. It wouldn’t be the first time poking a stick at Apple got the desired reaction of free publicity in all the media frenzy.

Analysis: how to build an OS X-free, expandable Mac