Is A 1080p HDTV Worth Buying Now Or Not?

1080p is much better than 1080i. Though you probably won't be able to view that much of difference between 720p and 1080p unless you have a plasma TV larger than 61".

1080p means that there are 1,080 vertical lines of resolution. The "p" means that this picture has "Progressive Scan" technology which means a more frequently refreshed, clearer, picture for you.

1080i is basically the same except the "i" dictates that this is an interlaced image and isn't as frequently refreshed as 1080p.