On the election calculator, I had the map left blank and started tallying all states east of the Missippi River. By doing those states only, I have Obama at between 225-240 votes and McCain between 73-88 votes. I have Obama taking PA and the 225 votes for him is if NC goes to McCain. The 240 is if NC goes to Obama.
Now I put the votes in for MN, IA, MO, AR, and LA. Obama leads 253-103 with McCain taking North Carolina. Now if North Carolina is taken by Obama, that will put him at two shy of the magic 270. Nebraska splits their votes like Maine (I gave all four Maine votes to Obama) and that state could nudge Obama over 270 due to those split votes. Now if Obama does take NC and two NE votes, he wins the election at 270 votes even before the rest of the West's votes are in.
Assuming NE gives McCain all five votes, where Obama could win the election is NM and CO.
Another situation is that I put all three west coast states in blue and HI in blue with AK in red. Even without counting the states between the west coast states and the Missippi, Obama still wins the election with 317 votes to McCain's 76.
Now if you don't count IL, WI, and MS but the west coast states plus HI and AK in addition to McCain winning NC, Obama still has 271 votes.