Each candidate needs at least 270 electoral votes to win outright, and a tie at 269 that throws it into the House isn't impossible.
Obama | McCain
Votes Probability | Votes Probability
230+ 0.9882 | 230+ 0.4442
235+ 0.9841 | 235+ 0.3829
240+ 0.9789 | 240+ 0.3253
245+ 0.9723 | 245+ 0.2724
250+ 0.9639 | 250+ 0.2249
255+ 0.9532 | 255+ 0.1834
260+ 0.9398 | 260+ 0.1479
265+ 0.9230 | 265+ 0.1180
266+ 0.9192 | 266+ 0.1126
267+ 0.9152 | 267+ 0.1075
268+ 0.9111 | 268+ 0.1026
269+ 0.9066 | 269+ 0.0979
270+ 0.9021 | 270+ 0.0934
271+ 0.8974 | 271+ 0.0889
272+ 0.8925 | 272+ 0.0848
273+ 0.8874 | 273+ 0.0808
274+ 0.8820 | 274+ 0.0770
275+ 0.8764 | 275+ 0.0733
280+ 0.8454 | 280+ 0.0573
285+ 0.8087 | 285+ 0.0444
290+ 0.7659 | 290+ 0.0343
295+ 0.7174 | 295+ 0.0262
300+ 0.6635 | 300+ 0.0199
305+ 0.6050 | 305+ 0.0149
310+ 0.5432 | 310+ 0.0111
315+ 0.4797 | 315+ 0.0081
320+ 0.4157 | 320+ 0.0058
325+ 0.3533 | 325+ 0.0041
330+ 0.2940 | 330+ 0.0028
335+ 0.2394 | 335+ 0.0019
340+ 0.1902 | 340+ 0.0012
345+ 0.1475 | 345+ 0.0008
350+ 0.1115 | 350+ 0.0005
355+ 0.0822 | 355+ 0.0003
360+ 0.0592 | 360+ 0.0002
365+ 0.0414 | 365+ 0.0001
370+ 0.0285 | 370+ 0.0001
375+ 0.0192 | 375+ 0.0000
380+ 0.0126 | 380+ 0.0000