The JR 7 day unlimited train pass?

I'm going to Japan next week, and I'm going crazy trying to figure out what seems like a very complicated train system. Specifically, I'm trying to find out if it makes sense to buy the JR 7 day pass, which has to be bought before I get to Japan, and gets you unlimited train travel for 7 days for about 283000 yen. I am going from Tokyo to Osaka, Kyoto, and Nara and then back to Tokyo. Can anyone tell me how much regular train fares tend to be? Thanks.

If you do Tokyo-Osaka-Kyoto-Nara-Tokyo within 7 days, a 7-day pass will come cheaper than regular train tickets.

How to travel between Tokyo and Osaka:
http://www.japan-guide.com/e/e4006.html

Between Osaka and Kyoto:
http://www.japan-guide.com/e/e4006.html?aFROM=2157_2158

Between Kyoto and Nara:
http://www.japan-guide.com/e/e4107.html

Between Nara and Tokyo:
http://www.japan-guide.com/e/e4107.html?aFROM=2164_2165

if you're going next week, you better make a decision soon. I think it takes a few days to get the JR pass.