What's the oldest MS VC version Parrot should built with?

[Ron Blaschke]

Currently, the oldest Visual C++ version Parrot should be built with is
VC++ 7.1 (aka cl 13.10,) included in Visual Studio .NET 2003).  Should
we raise this to VC++ 9.0 (aka cl 15.00,) included in Visual Studio
2008, Visual C++ Express 2008 or the Windows SDK 6?)  This would be
tempting, because

* VC9 is more easily available, through gratis download.  There used to
be a free VC7 bundle, but Microsoft pulled it in favor of the Express
editions.

* VC7 is a bit weak on the floating point side.  You probably noticed
+/-0.0 test failures.  If we keep VC7 we need to work around this.

The only good reason I can think of to keep VC7 is because it's the last
version to support Windows NT.  VC9 targets Windows 2000 and up (XP,
Server 2003, Vista).

Ron