Bharhav:

You may be confused.

There are 4 recent versions of Visual Studio, each with its own version
of the Visual C++ compiler:

Visual Studio 6 (VC6)
Visual Studio 2002.NET (VC7)
Visual Studio 2003.NET (VC7.1)
Visual Studio 2005 (VC8)

And there are two kinds of programs

Native Win32 (or Win 64) programs
Programs that require the .NET runtime

So (due to a crazy naming decision by Microsoft marketing), .NET can
have two meanings. Try to forget that Visual Studio 2002/2003 have the
.NET in their name.

All four of the above versions of Visual Studio can generate native
Win32 programs. Each version of the compiler is better than the one
before, but many people still use VC6 because they prefer the IDE.

Visual Studio 6 cannot be used to generate native Win64 programs, but
the others can.

Visual Studio 6 cannot be used to generate programs for the .NET
runtime. The others can, but they support different versions of the runtime:

Visual Studio 2002: version 1.0
Visual Studio 2003: version 1.1
Visual Studio 2005: version 2.0

HTH,

David Wilkinson

To add to David's fine answer:

Each new version of VC++ has been more standard compliant than the one
before.  VC6 is non-compliant in many many areas, VC7 a little better.
VC7.1 was a huge leap in conformance, and VC8 makes minor improvements
beyond that.  If you're interested in portable C++ code, you're best off
using VC7.1 or VC8.  Large open source C++ libraries like Boost compile with
VC7.1 and VC8 and work perfectly.

Each compiler has generally seen optimizer improvements as well, so code
compiled with the same options will generally be faster when compiled with a
newer compiler.  Confounding that trend, some defaults have changed, and a
great deal more runtime checking has been added to debug builds, so while
fully optimized release builds have gotten faster, debug builds have gotten
slower - in some cases a lot slower - but the additional runtime checks will
help you identify and locate a large number of bugs that the older runtime
library would have let you get away with (or simply crashed mysteriously).

As David said, many C++ users have stuck with VC6 because they prefer the
IDE.  In my experience, those are users that are heavily invested in MFC,
which has much better IDE support in VC6 than in the later versions.  If
you're not using MFC (and if you're worried about portable code, then you
shouldn't be using MFC), then the differences in the newer IDEs are much
less painful.  For my own work, I found that after I used the new IDE for a
couple weeks, I much preferred it over the VC6 version.  Your mileage may
vary.

-cd