advice on buliding browser-based (non CHM) help system

[Andrew Strombeck]

Hello,
I'm new to this list, but have found it a rich resource in the past. Let me apologize in advance for the general nature of this question, but I'm having trouble finding a succinct answer elsewhere. 

I'm writing user docs for a browser-based application built in .NET. Since the application is for internal use, the developers have standardized on Internet Explorer.  

In lieu of using a full Microsoft CHM file, I want to write help as a series of HTML (or XML) pages. When called, these will display in a floating window that users can access without opening a new browser window (this part is taken care of by the developers, using something called RAD controls). 

Each page needs to display in a context-sensitive manner, i.e. when the user clicks a ? button on a form, help will return a topic related to that page. At the top of this page, I want to integrate a simple search that will look through all the help pages in a directory and return a list of pages with matching terms. 

I'm using Help and Manual as a development enviroment.Table of Contents isn't terribly important. 

I basically need advice on two things: 

   implementing context-sensitive help without using a CHM file and
   implementing full-text search on the directory where I'll store my Help files
Thanks in advance.

Best,
Andrew