I bet on a Ferrari 1-2 with Massa in first. Third place to Hamilton.
However, everything might happen. McLaren is better than Ferrari on corners, but lose on straights, while Ferrari loses on corners, but wins on straights. Have you noticed that McLaren won at Monaco this year with Hamilton and last one with Alonso, and that Ferrari won twice in a row at bahrain and thrice in a row at Istanbul, all with Massa? Monaco clearly favors McLaren, while Bahrain and Istanbul favor Ferrari. These two are both fast courses, while Monaco is the slowest in the season. So, fast courses favor Ferrari and slow ones favor McLaren... Spa is a very fast course, and that clearly un-favors McLaren (in short, it favors Ferrari), wich means that Ferrari should do better than McLaren on this weekend's GP, but, as I said before, everything might happen...