64-bit processors - the next generation
If you buy a new PC today, it will have a 64-bit-capable CPU installed. The reason for the move to 64-bit CPUs from 32-bit CPUs is largely due to the limits in the amount of memory that 32-bit CPUs can access. A 32-bit CPU can, at most, address 4 gigabytes of data. For many purposes, that's fine, but once you step into more demanding applications, be they gaming, video processing or even working with large databases, it becomes a limiting factor that slows system performance. As main memory in desktop PCs creeps higher and higher, we're getting closer and closer to that 4GB barrier.
A 64-bit CPU isn't hampered by those problems, as its increased addressing space of 64-bits versus the current 32-bits, allows it to address up to a potential 16 exabytes of memory -- that's 16 billion gigabytes, quite a jump from the previous generation. Having a 64-bit data path also doubles the amount of data that can be fetched at any one time, increasing data throughput within the processor itself.
The earliest 64-bit processors were server-based affairs designed explicitly for 64-bit operating systems, but the current crop of 64-bit processors, first seen in the consumer space with AMD's Athlon 64 line of CPUs. Consumer-level 64-bit CPU like the Athlon 64 can handle both current 32-bit operating systems and software, as well as true 64-bit software designed specifically for a 64-bit CPU. So with a 64-bit CPU, you're still going to get solid performance from existing applications, as well as a touch of future-proofing when 64-bit applications become more solidly mainstream. For the moment, the best work you can get out of a 64-bit CPU is in the gaming arena, as the CPU-intensive nature of gaming -- combined with several gaming engines which have been or are being optimised for 64-bit computing -- give gamers a solid edge.