After reading about seo i get the impression that keyword tags are no longer used as a factor in pagerank if this is so is it worth still using the keyword tag or will we have are pr decreased for doing so
Pagerank has never had anything to do with keywords, content or any other on page factors. PR is all about the number and PR of the links coming to your website. http://en.wikipedia.org/wiki/PageRank The keyword tag may not have any effect but you should still use it. You should also use the description tag.
One advice for using the Keyword tags is not to stuff too much into the tags... avoid Keyword Stuffing.
Best advice I can give you is to forget you ever learned the word page rank. Completely wipe that out of your head and move on.
I still use the keywords tag on all of my sites, although I'm not sure whether they're still of SEO value or not. When in doubt, I typically view the source of some "no-brainer" authority sites, e.g. Microsoft, Adobe, etc., and do what they're doing. I don't think using this tag can hurt you, unless you use it for keyword spamming (as mentioned above) - limit your keywords/phrases to three or less, and you should be good to go. Sam