Hi DP. I need your help on this. I do recall reading that if you suddenly change the content on your site, you can lose your Google PR status. Currently I am getting designers to design a homepage for my forum - http://www.advertisehotspot.info/ http://www.advertisehotspot.info/ is the link to our forum and it has never been /forum or something like that. So if I put our new homepage and set it as http://www.advertisehotspot.info/ and our forum to /forum will our http://www.advertisehotspot.info/ link lose all our PR? Current PR is 4. Thanks!
If you're just talking about toolbar PR, I wouldn't worry too much. It is updates so rarely and means a lot less than it used to. As long as your existing backlinks remain, I don't see why it should radically change. I have noticed that a complete redesign might change your SERPs for a little while, but it shouldn't be for too long. I've even had some sites gain in the rankings after installing a new theme. I say go ahead and do it.
I also agree. Sometimes making major site changes can have short term negative impacts. But keeping your site fresh and functional can ultimately bring in more traffic in the future.
New content could indicate your site is starting over again and could loose its rankings, especially your pages that previous rank on certain keywords and contents. Expect this losses if you decided to change things, your site culd be treated as new one.