how to use Server.htmlEncode

Hi,
we have a forum site in which we want to allow our users to inject html content which should not be rendered on the site but it should just disply as a text on the page with tags.
On the web every one is saying that turn off ValidateRequest flag and use htmlEncoding. i tried that and that works fine in my site. But msdn articale http://msdn.microsoft.com/en-us/library/a2a4yykt%28v=VS.90%29.aspx says that this is not recommended.
so
1. I want to know like what can be the recomended implementation of this feature
2. What are the impacts if I implement this with htmlEncode and ValidateRequest="False"
 
Thanks in advance
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