Replacing Hard Drive in Dimension 8100

I am not even sure that I need a new HD. I got the "F1 or F2" message, then emailed Dell support. They accessed my machine, and then I got a message telling me that "controller is operating outside of normal specifications, immediately back up data, replace hard drive by calling Dell." They also sent me a generated email that took me through some diagnostics. Ran them all. Got no error messages but continue to get the "F1-F2" message. I then called Dell, talked with a person who took me through diagnostics. Still got "F1-F2". He then had me look on back of tower at 4 lights. Three were green, one amber. And I mentioned the message about "operating outside...etc.". He immediately said that he would replace the HD and would call me back with a dispatch number. He has not. But once I do get windows to open, I see that all 4 lights are green. In addition, my 3 yr. warranty expired three weeks ago, so I question whether they really will replace my HD. I suppose that any replacement is on me, but I am not at all sure what to replace it with. My online info shows this about HD: 044WT HD 60G 1,7.2k, 3.5" Form Factor, IN 20/P, MAXTOR. My shipping form shows 60GB ULTRA ATA HARD DRIVE (7200RPM). Can someone tell me just a simple line of specifications that I should look for in shopping. I want to replace with a HD that will work but don't understand this F100 or F133 and such.

Thanks,
Jerry