my 27" late 2009 iMac's Seagate drive is now failing. Here is the drive currently installed: ST31000528ASQ 1 TB 2.8 GHz Intel Core i7 8GB memory The warranty has expired Questions: 1) Should I replace this drive with another Seagate or perhaps a WD that may last longer? 2) How much does it cost roughly to replace this? Should I buy one from mac mall or something and find someone to replace it? 3) It won't let me install Lion because it says it is failing, even though it is running fine and has been for a good while in this state. Is there a workaround to install Lion without replacing it first? thanks!!!