Online banking uses 128bit encryption (kind of like a made up language - your computer speaks French. You don't so it's going to be really hard to learn). The time required to crack a 128bit code is about 1000 times longer than the current age of our Universe and requires an ubercomputer* that can handle a billion billion calculations per second.
*IBM's current best supercomputer "BluegeneL" handles 70.7 trillion calculations per second - that's nearly 71 trillion calculators working at the same time on different math things.
The only computers that MIGHT be able to do it is the MDGrape3, which they haven't even worked out exactly what it can do yet or IBM's similar system, "Roadrunner", which can handle a phenomenal speed of 1.4 petaFLOPs per second. Even at these unthinkable speeds, it's still not going to crack 128 any time soon.
Needless to say, they aren't going to be on the public market any time soon - Roadrunner occupies a space of over 560 square meters and requires it's own powerstation to run! To show the sheer scale of these machines, your average home PC only handles about 100 million calculations and runs at a speed of about 3 gigahertz -roughly 30 million FLOPS. A petaFLOP is a quadrillion FLOPS. (For detailed chart: Wiki Giga)
Interesting Fact of the Day: It turns out "e" is a number = 2.71828183. It requires some serious thinking time to explain.