Windows Vista 32-bit can address up to 4Gb of memory. Although that sounds a lot, some applications would benefit from more and – a crucial point here – that 4GB limit includes graphics card memory. So buying the latest graphics card with 1GB RAM onboard will seriously eat into the amount of RAM that can be addressed by a 32-bit processor.
In comparison the 64-bit version of Vista can address 16Tb of memory (yes 16,000 GB). Not only that but programs that have been written for 64-bit use will run faster and the system will make better use of the latest hyperthreaded multi-core processors.
The major drawback of the 64-bit version of XP was the poor level of support for device drivers. Things are now much improved with far fewer driver problems,although it is still true to say that it is best to check whether drivers are available if you need support for specific hardware devices. Beta versions of Windows 7 are available in 32 and 64 bit versions but the emphasis is likely to be on the 64-bit version, at least for PCs above entry level.
It may be a great relief to hear that Vista and Windows 7 64-bit versions work fine with 32-bit programmes. The only things to watch out for are 32-bit programmes that use a 16-bit program to install themselves (and which won’t run) and programmes that address hardware directly, rather than using a driver.
And here is a final thought – as many as 20% of new PCs sold in the US now come with a 64-bit version of Windows. The buyers can’t all be wrong!