Microsoft must be really sick and tired of dealing with Windows XP. The OS is ancient, in computer terms, it's falling behind in security features that can't readily be improved because of it's older technology, and Microsoft keeps having to support it because we won't give up on it! Any time they can point out how much better Windows 7 - or Windows 8 - is, you can bet your sweet bippy they will. To that end, their Security Intelligence Report for the first half of 2012 says the company had to remove malware twice as often from XP systems and Vista or Windows 7 ones. Ooof.
Except it may be a little less dramatic than that, in reality. Microsoft's Malicous Software Removal Tool (from which the stats were pulled) only detects some malware, and is quite selective. So it's hard to know how accurate the information really is in a real life type of comparison. While the general premise is valid - that Windows 7 is "better" than XP, and more secure - I think Microsoft may be going to town here to try and cast off the XP albatross for good.