First, the simple answer is that no matter who did it, it is a horrible event. BUT, if it is the ETA, then it is a problem which is contained, and does not effect me. If it was AQ, then it is a significant event in terms of the health and strength of AQ as a global threat.
As for Oklahoma, and the quick trigger to blame Muslims, as I remember that , the finger was pointed at Muslims for about 24 hours until facts became clear. And was the "Arab Terrorist" fingerpointing without reason? No, After the first AQ attempt on the WTC, it was perfectly rational to believe that there might be some involvement, and the suspicions keep getting stronger with every AQ bomb.
Look, I don't blame you all for flinching everytime some commentator says "Muslim Extremeist", as a potential suspect. It must hurt like hell to be painted with a brush that none of you deserve. But, denunciations of AQ have not come from all quarters of the Muslim world. OBL still has dedicated sympathisers at radical mosques around the world. He is still being funded, protected, assisted and sheltered right in your back yard of Pakistan. (we think) You, as a community of Muslims can do far more about his future than I can.
In the mean time realize that with each additional attack over that past couple of years, AQ has established itself as a global threat. This is an order of magnitude different from the ETA, the IRA, some isolated moron in any given country, or some stupid white supremacist movement with three guys without teeth and a nasty hate filled web site. AQ is a legitimate threat, and deserves every bit of the attention it gets.
Rather than rail at those who simply recognize this threat, understand that discounting the possibility that Madrid could be the same as Istanbul, makes people look defensive and unrealistic. I beleive, given the facts that are out there today that there are many possible culprits.
BUT, if AQ has struck Europe, it is a far bigger deal than ETA changing tactics. Certainly for those of you living in Europe, the ramifications are far more profound....