hi there dp friends, i im currently updating my main page, change and add some text info. my question is, this can affect my site on SE's? can this cause a bad effect or what? can this affect also on my pagerank? and SE's results position? any help is appreciated. thanks
Any text changes can affect your rankings - either positively or negatively. PR has nothing to do with content - it is only determined by sites linking to yours.
Archie, if the changes are basically in your main page's text, you'll probably be fine if you are improving your choice and use of keywords on the page. Lots of us are continually "tweaking" text to make better use of the keywords appropriate to that page. It's also fine to change the wording of your title to make better use of your chosen keywords. I've done this often, with considerable positive results in SE rankings. I'm sure you know this, but don't change your URL, or the search engines will be disconnected from that page and you'll be starting over getting that new URL indexed.