If we use new subversion of html as HTML4.0 or HTML4.1. What are the benifits of it. It helps us for ranking better in search engines or it give us any other benifit?

It helps us for ranking better in search engines or it give us any other benifit?

The version of HTML you use has ZERO bearing on page rank.

You will see very little difference between 4.0 and 4.1

But, if you move up to XHTML and start implementing at least some of the CSS tags you will see some effects on your page that make it look just a little less plain that HTML.

Search engines don't know the difference but your users will see the differences.

Good solid content will be the best thing you can do to guarantee better search results. And it doesn't hurt if you have a hot topic people want to see.