I don't think the Egyptian regime will fall any time soon, all the vested interests who control Egypt have too much to lose if Mubarek is toppled. As Egypt is home one of the busiest shipping routes in the world this matters a great deal.
Unless you know what would take it's place a revolution is a very big gamble for all concerned. Still it is depressing to see a resurgence of the idea that the West should continue to back the likes of Egypt because other wise the Islamists will take over.
It is similar to the misguided policy of the Cold War to cooperate with strongmen with appalling human rights records because they proclaimed themselves to be anti-communist- usually opportunistically. The policy of backing nutters like Joseph Savimbi or General Suharto did more to sully our image than every Marxist tract ever written.
There isn't much evidence that the Islamists are the ones poised to take advantage of the void left by Mubarek, as the Economist's Lexington points out there is usually a ceiling of about 20% in terms of support for Islamists in Muslim countries.The protesters aren't demanding a Caliphate and even the usual "Death to Israel" banners aren't widespread. Whilst we shouldn't openly work against the Egyptian government, there is little to be gained from propping them up either.