Hard Disk Error Code

I have a Dell Studio XPS 8100 desktop computer, purchased in December 2010, running windows 7. Several days ago I was suddenly unable to get my computer to boot up to windows, even in safe mode.  Tried doing the repair (after pressing F8 at startup), without success - the computer would only boot to the blue screen with the Windows backgound, but would not load the rest.

I decided to run the Dell Diagnostics, and originally got the following Hard Drive Error Message: "Error code 0146; Msg: Error Code 2000-0146: Msg: hard drive 0 - self test log contains previous errors".  I then ran the symptom based diagnostics for "Cannot boot the operating system" and when it got to
SATA Disk S/N=9VPAP3Q - Confidence Test, I am getting repeated Error messages of the following: "Error Code OFOO:1332 Msg: DISK - block 71xxxxxx (varied numbers): Interrupt Request (IRQ) did not set in time".  This test has been running for about 2 days now!

I did just order a replacement hard drive, based on previous messages/posts I have seen.  Is there any reason I should allow this test to continue running?  Is there any other tests or any other actions I might try to get the computer working again before replacing the hard drive?

I did forget to say that I did have a similar problem back in April, and we did a complete re-install of Windows 7 at that time.  I am assuming that the hard drive may have been starting to fail at that time also, and we just bought a little more time. 

I appreciate any advice or suggestions.

Thanks,

Kathy