When Ubisoft launched the fabulous First Person Shooter (FPS) Far Cry in 2004 it did so on a single DVD, rather than the stack of three CDs that you might expect. While this was a welcome move for all of us who have become sick and tired of juggling discs during the installation process, there was another reason for this move. Ubisoft had originally intended to include two versions of Far Cry on a single DVD, so you'd have got the regular 32-bit version to run on Windows 98, Me, 2000, XP Home and XP Pro, as well as a 64-bit version to run on 64-bit Windows.

As you may be aware, the release of Windows XP Professional x64 took an absolute age, so Ubisoft got on with the job and released the game in a 32-bit version. Well, Microsoft finally got its act together and released Windows XP Professional x64 in April 2005, so Ubisoft has released a 64-bit update that is free of charge and that allows you to run Far Cry natively under 64-bit Windows.

Of course you need a 64-bit processor, so that's an AMD Athlon 64, AMD Opteron or, perhaps, an Intel 6xx Pentium 4 processor. While you may be able to run one of the many time-limited Betas of Windows XP Professional x64, this isn't a good idea if you want your PC to be as stable and reliable as possible so it's best that you spend £95 on the official release of the software.

Once Windows is installed you need to check that all of your hardware is working correctly, as 64-bit drivers are completely different to their 32-bit brothers. If our experience is anything to go, by the problem areas are audio and networking, as integrated hardware requires specific drivers from motherboard manufacturers, rather than the likes of Creative, Marvell and Broadcom.

Assuming you've got past that stage you can install the retail 32-bit version of Far Cry, plus the 74MB update to version 1.3, followed by the 9MB version 1.31 patch. Then you can head to www.farcry.ubi.com where you'll find a list of sites that are hosting the 64-bit updates. You need two files which are 421MB and 485MB respectively, so this is strictly one for Broadband users, but we found the servers were very fast and got both files in an hour thanks to our 2Mb cable connection.

Once the game was installed we started to play and frankly we were unable to tell the difference between the 32-bit and 64-bit versions. Or rather there were differences but they didn't seem to have anything to do with the 64-bit aspect of the PC but instead looked like they could have been introduced with a simple update to the existing game.

For instance, any number of boulders now have enhanced bump mapping to make them look more realistic. That's a laudable aim but, let's face it, a piece of granite doesn't have much in the way of a surface texture so the designers at the developer Crytek have clearly felt the need to make every last rock in the game appear as a moss covered monolith to 'prove' that 64-bit is better than 32-bit.

We were put through a similar process when nVidia launched the GeForce 6xxx series of graphics cards, as they support DirectX 9.0c with Shader Model 3 (SM3) while ATi can only manage DirectX 9.0b with an enhanced version of SM 2. This made it essential that Crytek (as a partner of nVidia) released a patch for Far Cry to display the benefits of SM3, thus every last cavern wall and corridor surface became more textured and bumpy. While the updated game looked different on the new graphics chip if you knew what you were looking for, it was hard to claim that it was actually better.

It's much the same with this 64-bit update. For instance, to demonstrate the improved draw distance that 64-bit software allows, the binoculars allow you to see objects that are further away, so instead of just seeing a mountain in the distance you can now see the enemies on that mountain and the weapons that they are carrying. It looks good but it doesn't enhance the gameplay at all.

The only part of the single player game that has changed significantly is the Pier level where the map has been enlarged. It's not an especially interesting area (shoot men waiting for you in long grass, shoot men in a watchtower, blow up explosive barrels) and we are prepared to bet a sum of cash that this area was intended to be in the original version but wasn't ready in time, so it was simply sealed off in the 32-bit software.

Crytek has also included two new multiplayer levels called Gorge and Stronghold, but again we don't really see why these couldn't be made available to players of the 32-bit version of Far Cry.

The 64-bit version of Far Cry promises plenty but it actually delivers very little. Keep telling yourself that it's free of charge and does at least work flawlessly on the latest version of Windows and you'll be happy enough, but in no way is this game a reason to upgrade your operating system.