Not to upset google
Hi. I remember having read in the past that if google finds that the majority of the pages of your website are not where it knows they are, it kills your PR.
I am concerned. I had to move a huge part of my site from the root of the domain to a folder.
is it enough to put a permanent redirect in .htaccess?
my goal is not to lose the the remaining poor PR2.
PR is page specific. If you move some other pages it's less likely to affect your overall PR. But if there are many broken links etc because of the move your overall PR might be affected.
Yes your pr will be effected if the url are changed. There is no doubt about that.
And yes it is possible to redirect the domain to a folder or sub-directory using .htaccess. But I got only little knowledge on this. If I provide you suggestion, this might get even worse. So, I recommend you to do a search in Google. You can find many descriptive explanations and tutorials from expert.
PR only depends upon the number of quality links pointing to a particular page.