AMD launched its Opteron processor in April 2002 and since then we have been waiting for Microsoft to fully support this innovative processor with a 64-bit version of Windows. After two years of Beta versions, we now have RC1 (Release Candidate 1) of Windows XP Professional x64 Edition in our hands. So long as there are no setbacks, the software will be released to manufacturing in March, with a planned launch date of 29 April. If you’re interested, you can go to www.microsoft.com/windows and follow the link to 64-bit, where you’ll be able to download the 556MB file.

TALKING CHIPS

Opteron is an unusual processor as it can run both 32-bit and 64-bit software natively, unlike Intel's Itanium which is a native 64-bit CPU, so it can only run 32-bit code such as Windows XP in emulation. The operating system is a fundamental part of your laptop, but in an ideal world it would be transparent to the user, as its job is to tie your hardware together with drivers to allow software to run properly.

The only parts of Windows that you really need to be aware of are the desktop, System Tray and Start Menu and, as you'll see from our screenshots, there are no visible differences between the 32-bit and 64-bit versions of Windows XP. If you look very closely, you'll be able to work out that we installed RC1 on a desktop PC, rather than a laptop, and the reason for our wimpish behaviour on this front is the age-old issue of hardware and driver support.

Software and drivers need to be specifically compiled for the Operating System, which is the reason that you can't run Mac software on Windows or PC games on Linux, and also why you'll find a printer comes with one set of drivers for Windows 98/Me and another set for Windows 2000/XP. Although Asus, the maker of our test motherboard, doesn't have any 64-bit Windows drivers listed for the SK8V model, we were impressed to find that is was quite easy to track down Beta drivers from VIA for the chipset, nVidia for the graphics and ADI for the integrated audio.

The integrated LAN from 3Com didn’t work, as Windows refused to recognise the chip, which probably means that Asus has modified it. However, an Intel PCI 10/100 Ethernet card installed and worked perfectly. A PC is a collection of parts, but a laptop is so highly integrated that you need driver support from the manufacturer or you're in trouble, which brings us to the question of which CPUs and laptops can run 64-bit Windows? Basically, you need a desktop Athlon 64 or Intel Pentium 4F CPU, although Intel has a Celeron 64 that’s almost ready to launch, so you’re looking at a desktop replacement laptop. True mobile processors, such as Pentium M, don't currently support 64-bit extensions, and for now aren’t a priority compared to power saving and the move to dual core. However, there is no doubt that 64-bit will come to the mobile market, once it is established in the desktop arena; although it may be in Windows Longhorn rather than in Windows XP.

So we have Windows XP Professional x64 Edition on our test PC, but what good is it to us? A 64-bit OS can handle much longer numbers than a 32-bit OS, so you can either store longer numbers or you can specify numbers more precisely, but the most obvious feature is support for more system memory. The 32-bit version of XP can address up to 4GB of RAM (2GB for the OS and 2GB for applications), but the standard version of Windows x64 can address 32GB of RAM, although this feature is likely to be irrelevant to the mobile market for at least two years as 1GB of RAM is luxurious at present. If you make the move to Windows x64 you'll find that the majority of your software will run flawlessly thanks to the WoW64 Emulator (Windows on Windows), but you can expect that some software will break, because that is inevitably the case with new versions of any software.

You won't, however, notice any difference in the way that your 32-bit software works when it runs on WoW64, and neither will you see a difference if the software manufacturer recompiles the software so it runs natively under a 64-bit environment. Where you will see a difference on laptops and PCs is when you get true 64-bit software, and here we can expect games to lead the way. It is quite feasible for a games designer to develop a map where you fall from outer space towards a planet with the view zooming in closer and closer until you can pick out individual pebbles and blades of grass, and no doubt we will see games that use 64-bit features purely because the technology is available. In short, Windows XP Professional x64 Edition will make little or no difference to your mobile experience in the short term, but it's a significant step towards the happy day when you have 8GB of memory in your thin and light laptop.

RATING 8
RC1 is free of charge but time limited
KEY FEATURES 64-bit Windows, so long as you have a compatible processor
SYSTEM REQUIREMENTS AMD Athlon 64, AMD Opteron, Intel Xeon with Intel EM64T support, Intel Pentium 4 with Intel EM64T support processor, 256MB RAM, screen resolution of 800 x 600 pixels or higher
CONTACT
www.microsoft.com/windows