IBT on at least standard stress level is a good test of stability. High stress level is preferred - assuming you have enough RAM. As Ast3r said - don't really worry about the results, it's not a benchmark. Provided it finishes the test, within safe temperatures, and there isn't massive variance between the results, then you'll be fine.
By the way, TechPowerUp! is also a good place for little programs like IBT, GPU-Z and such.