I'm a huge fan of Ricky Gervais, but I must point out that Steve Carrell didn't rip his show off.  Gervais & Merchant sold the orginal idea to NBC, and act as producers.  It's a total collaboration.  And they are all good friends.  Further, the british version is very different then the US version.  Ricky Gervais' character was much more difficult to feel sorry for (but still funny as hell), whereas Steve Carrell's character is much more sympathetic.  you feel quite sorry for him.