I am newbie to Tex. Only downloded it a couple of days ago, but since then have been furiously trying to make it work with Hindi. A couple of hours ago, I succeeded with the following combinations:
-miktex distribution of Tex
-Lyx as the editor
-XeLatex as the pdf generator
In miktex the devanagari package under indic languages in language support must be installed.
This installs the velthius package for Hindi-Sanskrit and its precomplier.
You must also install fontspec package in miktex.
All these package are there in the proTex distribution which you would have used to install mikTex.
Next download and install Lyx. On a new Lyx file, set the document setting as utf8-plain.
Next add the following code as the preamble for Latex in the Lyx file:
\usepackage{fontspec}
\usepackage{xunicode}
\usepackage{xltxtra}
\fontspec[Script=Devanagari]{Mangal}
You can now start entering your Hindi in the normal way as you enter Hindi text in Word or OpenOfficeWrite.
You will not be able to compile an output of this text through Lyx itself. For this you will need XeLatex.
After you have finished entering text, save it and Export it as Latex(pdflatex). This will generate a .tex file for you in the same directory as the lyx file. Run this file through xelatex with this command from a dos prompt:
c:>xelatex <full absoulte path of the .tex file>
This command will generate a pdf output for your file.
In place of Mangal, you can choose any unicode Hindi font in your computer as your Hindi font, but the script value should be kept devanagari for Hindi.
I am attaching the pdf output for a small Hindi para with this method for your reference.