Thanks for your inputs. I opened up the case, blew out the dust, and did the startup with the case open. Startup noise problem doesn't seem to be any of the three fans. Worst of all, I can't even tell where the noise comes from. I guess I need a stethoscope or something.
I also thought maybe some of the ungodly nest of wires was getting pushed into a fan, but doesn't seem to be happening.
The moaning/groaning noise is urgent enough that I don't let it run long. Sounds like end of the world is coming. But then everything quiets down and it funs fine all day once it likes what's happening at startup.
I'd be tempted to just let the computer run 24/7, but I did that with the previous hard drive and thought that was one of the reasons it failed after about the same length of time.
This last happened about 18 months ago. Same symptoms; eventually wouldn't run and so I replaced the hard drive. Can't believe this is happening again with a different hard drive from a different vendor.
I backed up my hard drive again today to an external drive. When drive failed last time, I restored most of system from the external hard drive. But it wasn't as easy as advertised, and wound up having most my stuff an extra layer deeper than optimum.
I guess I'll baby it through mid February until I get TurboTax done, then buy one of the last of the XP systems and hope that will last two years until bugs get worked out of Vista.
Really tired of computers taking so much time and money and requiring major upgrades or replacement every two to four years. But love what they do.