Check out CNN's electoral map today at:
http://www.cnn.com/ELECTION/2008/calculator/
This currently gives Obama 277 delegates to McCain's 122 with 87 Toss Ups. They way current polling trend is going, Obama is likely to win from the toss up column, Nevada, Colorado, Florida, Ohio & North Carolina and McCain Montana. That gives Obama 353 delegates to McCain's 185.
Some McCain states are becoming doubtful of late i.e. Indiana & Montana, but I am inclined to leave these in McCain's column. The popular vote gap may not be so wide, probably between 4 to 6 %.
Barack Obama should win at least 353 delegates if not more and that is a margin of 65:35.
Political Critic: http://politicalcritic.com/ is giving Obama 378:160 margin