I still wouldn't overhype this. It only helps M$ to boost their Win7/8 Sales.
Sure, sooner or later there might be an exploit, hack, w/e, but as for now i cannot find any evidence that this allready happened.
Also, a newer OS doesn't neccessarly mean that you're 100% safe.
Whenever a security breach has been found, all the systems using the OS are still vulnerable till the update which might come next tuesday fixes the issue.
The only way to make sure that your Computer isn't infected by something (no matter which OS you're using) is to disconnect (unplug) it from the internet and don't use any external media also used on other PCs (such as external HDDs, Flash drives, CD-R, etc.).
Everything else, OS Updates, FW and AV can potentially fail to protect you under certain circumastances.
Ofc. the risk is there and now even bigger then before for XP users and i wouldn't do anything sensible like banking anymore on a XP machine, but still i'd rather use an XP machine then running through a minefield, no matter if naked or not.