> Saxon.NET might be useful if you want to integrate it more
> deeply into an existing .NET application. If XSLT 1.0 is OK, use the .NET
> XSLT processor (System.Xml.Xsl), or use MSXML3/4.

1. A word of warning:
AFAIK  it is not recommended to invoke MSXML3/4 under .NET because
MXSML has its own garbage collection, which messes up with the .NET
garbage collector and may suspend indefinitely the thread on which the
.NET GC runs.

A safe way to use MSXML3/4 from a .NET application is to run MSXML in
its own process and to communicate with it out-of-process.

2. In case the .NET XSLT processor (System.Xml.Xsl) is used, the way
to achieve an additional degree of portability is to use EXSLT.NET
rather than some native extension functions -- for example use EXSLT
set.node-set() and not msxsl:node-set().
Thus the xst code will be readily portable to any other XSLT 1.0
processor that supports EXSLT in the same way.

--
Cheers,
Dimitre Novatchev