The difference is that each of those operating systems brought new
capabilities that users really wanted... win95 brought 32 bit support and
a better GUI; 98 brought support for USB and much larger hdds; 2k/XP
brought support for more RAM and even bigger hdds. What does Vista bring
that anyone really cares about?
1. For gamers, DX10. The biggest issue here is that Vista moved the
graphic driver model out of kernel mode space and into user space.
This means much better stability and overall performance when the
drivers are properly written by video card vendors. Even if the
drivers are badly written, it means they cannot crash the core
operating system components like they used to.
2. It solves a major problem: software development companies that have
been continually releasing software that requires admin rights on the
end user PC will find it very difficult to operate in the world of
Vista. This was the core issue at stake that led to most of the
securty problems that gave Windows a reputation as less secure than
Linux et al. For a while, MS placed an emphasis on allowing backward
compatibility and not breaking applications even if they are badly
written. Those days are over. Software companies that release
software that doesn't follow best practices are going to find their
shit doesn't work right under Vista. The unfortunate side effect of
that for Microsoft is that of course idiot users are going to blame
the OS first, which means for the next couple of years we are going to
have to listen to people bitch about how Vista broke their software,
when the truth is its the software and hardware vendors that have been
ignoring the writing on the wall that has been there for 10 years. And
sadly, MS gave the whiners a way to disable the security protection,
so that if they really wanted to they could open themselves up to a
world of viruses.
What can users do on Vista that they
can't do on XP?
From a general user's perspective:
Have the peace of mind that there kernel cannot be modified/patched by
an third party application like Norton AntiVirus, or even worse a
virus/worm.
From a gamers' perspective:
Play games against XBox360 users
Play DX10 games
There's a lot more from a programmers perspective but they get more
complex so I won't go there.