Since 2001, when Windows XP shipped, most users have hovered between 1 and 2 gigabytes of memory. That’s because 32-bit Windows really can’t use more than 2 gigs (technically 3 gigs).
With 64-bit Windows, however, there’s no real limit any time soon. I predict that within the next couple of years you’ll see 16GB machines become pretty common and when that happens, lots of interesting things will start to happen again for PCs.
One interesting thing will be virtual machines.
Running Windows XP within Windows 7 has a lot of utility to it as a developer but for most users, it’s largely meaningless. That will change as applications themselves start to be able to specify the conditions in which they run under.
One of the things that has held Windows back has been backwards compatibility. But virtualization largely eliminates that issue because you could simply have programs run in their own VM.
It’s a real shame that Microsoft is even making Windows 7 in a 32-bit form because it just delays the migration to 64-bit computing. The reason this is important is almost totally based on RAM. This sort of virtualization isn’t cheap when it comes to RAM usage. But virtualization will free Windows to go in many different directions at once. It’s the next big thing.