Proof here, with commentary from Slashdot:
From install time to GUI efficiency, Ubuntu beats Windows and is often twice as fast. Where Windows 7 is competitive, the difference is something the average user would not notice. The average GNU/Linux user is now getting better absolute performance from their computer as well as better value than the average Windows user.
Where have I heard this before? I’m running Linux Mint on my laptop these days, and it’s awesome. Compiz Fusion is really cool, and doesn’t seem to cause a performance lag. I can now use Linux with work… everythign I want to use the laptop for just works.