I am wondering if I will see a noticeable difference between 1080i and 1080p? I am asking this because I have a 1080i plasma and see 1080p plasmas and LCDs popping up all over, is it worth the extra cost?

1080i plasma ?? You meant 1080i inputs and 1080p display, right.

You probably won't see any difference for film titles on Blu-ray or HD DVD as there 1080p24 content can be probably properly converted to your displays native resolution transfered through both 1080i60 and 1080p60 sources.

Now if you upgraded to a display that could take 1080p24 or 72 or 120 input, thats another story. ;)