Are you bi-curious? In other words, do you struggle to choose between these two options: the intuitive icons-and-windows interface of the Mac operating system and the, erm, intuitive icons-and-windows interface of the Microsoft Windows operating system? If you cannot make up your mind, there is obviously something seriously wrong with you. Assuming you cannot afford psychoanalysis, you might want to consider downloading an emulator. Sometimes bizarrely shortened to 'emu', this is a program which imitates the function of another operating system so it can fire up the same applications and achieve the same results as the original. If you want to run Macintosh files on a personal computer, one emulation option is Executor ( www.ardi.com ), which, by its own honest evaluation is fast and portable but limited to older Macintosh applications. If you want to run PC files on a Mac, consider the Blue Label Power Emulator ( www.lismoresoft.com ), which promises to let you transport the entire PC software world to your Mac. Suckers for vintage contraptions may instead choose to play with historical emulators. The prime example is Russell Schwager's mock-up of the Enigma machine ( www.ugrad.cs.jhu.edu/russell/classes/enigma/ ), which the Germans used in World War II to encrypt military messages. Mr Schwager's machine means you can turn all your e-mail messages into Nazi code, thus ensuring your secrets are safe from everyone except a passing spook or prying spouse. Thrill-seekers who insist on possessing every game devised can benefit from the growing profusion of online game emulators. Until 1997, game emulation was just a niche activity indulged in by code-crunchers and coin-operated game machine fanatics. All that changed with the emergence of an emulator called Mame (Multiple Arcade Machine Emulator), which successfully mimics coin-operated game machines. The latest version (version 0.61) can play nearly 2,000 authentic arcade games from the late 1970s all the way through to the late 1990s - everything from Armored Scrum Object to Zwackery. Game emulators can seem singularly pointless. For example, do we really need a copy of Knuckle Bash, a fighting/ wrestling game which features an Elvis impersonator and a man sporting a moustache and wearing tiny shorts and knee-length boots? Emulators can also be technically terrifying. Actually installing one and using it requires the kind of courage you associate with extreme sport enthusiasts. You can recognise an unsuccessful emulator user instantly by his haggard expression, trembling hands and air of bewilderment. Emulators tend to spawn the kind of error messages that would intimidate Bill Gates: 'Rescan NetBios to prevent a triple hexenduction wipeout occurring' is the typical tone. To make matters worse, emulation has a tendency to spawn litigation. Nintendo and Sony are forever trying to settle scores with emulation outfits they accuse of common piracy. The People at Mame contend that replicating often ancient coin-operated arcade games does no harm because they are no longer being sold and the copyright owners have already milked them for all they are worth. Mame also argues that its work has cultural value, saying it is trying to conserve classics for future generations and that emulation is the only sane option because keeping the original boards in working order poses too many problems. The question that, nonetheless, looms is what happens when emulation companies start reproducing cutting edge games such as Blade II? Imitation may be the sincerest form of flattery but it can also be a legal and technical minefield - double trouble for those who cannot decide which way to swing. Confused by computer jargon? E-mail email@example.com with your questions.