I was waiting for someone to pipe up with the first (Danger), that's actually a subsidiary of Microsoft and not Microsoft. Regardless of that it shouldn't have happened, but then you've got look at Apple's own Cloud services and the pains it's gone through as has Amazon and Google (who have lost data themselves to a lesser degree). Cloud Computing is very much still in it's infancy and if people are trusting it with data then they are crazy. They should have had some kind of back up, I've yet to see a full post-mortem on how it happened and why. You should also note it wasn't using M$ own Azure software but rather Danger's own software than M$ inherited so whilst M$ can be seen to be responsible they aren't in regards to software. Also M$ ran a hands off policy with Danger. From what I gather it was caused by a upgrade done by Hitachi that wiped the systems out. If it's like a lot of data centres I've seen and worked in, then many don't do any off-line back up these days instead backing up to hard drive arrays just because of the sheer amount of data (think 100s of terabytes). Backing that much data onto tape takes hours if not days.
In any Apple's flaws are far closer to home, networking flaws that when copying across a LAN didn't. A Firewire bug that wiped out data (if not drives), Time Machine systems failing after a year and now this one. and that's one the ones I can recall.
The second is a nightmare to implement, a lot of malware targets PCs and have been doing that for years. If people suddenly shifted to OS X then OS X will have the same problems as Windows XP did, as much of the security OS X is riddled with holes. When SL came out it was obvious they only did a half-hearted attempt at security and much of the models are still the same from Leopard.
In Vista and Windows 7 it's far, far harder to install a keylogger, malware or anything else. In XP it's a doddle. Yet people still persist in using XP with it's attendant Administrative rights as standard. In Vista you have at least 3 layers (MRT, Windows Defender and virtual user profiles) to take out before you get to put a trojan into the system, with Windows 7 you have 4. In x64 you also have added protection in part to WoW.
Most bank thefts come from identity theft, which is system agnostic. You fool the person into entering fake details on a site that for all intents and purposes replicates a banks site. If you practice safe computing your data will be safe. If you're really paranoid use a bloody VM.