Beginning of the End for my hard disk?

I've had a Dell Inspiron 1525 running 32-bit Windows Vista for about two and a half years now, and I heard somewhere that the average laptop life span is only about 2 years -- so I'm thinking this is the beginning of a rapid end.

A while ago my machine started getting a bit louder, but I thought little of it (or rather, thought it was just age starting to creep up on my machine).  A few days ago I started hearing some very nasty noises.  I presumed it was just a fan that maybe had gotten too much dust sucked in.  I got a pressurized air tank and carefully tried airing out the laptop through some of the air vents.  No luck, and after listening to the noises, I decide it's more of a grinding noise and (a day or two ago) that it could be the hard disk.  I'm afraid.

The grinding keeps getting worse and happens more often.  Mind you, it's inconsistent; gone for 10 minutes, back for 30 seconds.  Gone for 2 minutes, back for 2 minutes.  Comes and goes.

Today I've started running a battery of tests.  I started with WD's HDD Lifeguard extended test, which came back as a FAIL due to bad sectors (error code 08- I believe).  It says it can repair them but discovers an error, which I presume has to do with the fact that the drive is in use.  I switch to bootable tests, and (previously unknown to me) Dell's built in Diagnostic Tools are proving quite helpful.  The first time I tried to run the whole battery of tests from the "Symptom Tree" window available for Hard Drive Errors.  It skipped the Confidence Test for some reason, but the Device Quick Check comes back as a Pass.  The SMART Long Self Test comes back error code 0F00:065D "The self-test failed the read portion..."  After that every test I run freezes the machine for about 5-10 minutes and eventually comes back as an IDE Timeout error, including a second Device Quick Check.  I restart a couple times and go back to Symptom Tree, where I am at present.

(On reboot, initial tests, including memory, all pass, with exception of the hard drive test, which says, "Error code 2000-0146: Hard drive 1 -- Self test log contains previous error(s)," and asks if I want to continue with tests.  If I say no, it reboots system.  If yes, it skips rest of hard disk test, everything else checks out, and eventually I get to Symptom Tree menu in Diagnostic Tools, which results in following hard drive test results:)

(Shown here in the order the tests were run, including reboots. Note that I ran some tests a second time with differing results.)

Confidence Test -- Pass

Device Quick Check -- Pass

SMART Short Self Test -- Fail -- Self-test failed the read portion of the test (Error code 0F00:065D)

Read Test -- Fail -- Block 97822848 (31%): Timeout waiting for IRQ to respond (Error code 0F00:0232)

SMART Long Self Test -- Fail -- Timeout waiting for IRQ to respond

(Reboot)

Seek Test -- Pass

Start unit (Idle) -- Pass

Stop unit (Standby) -- Pass

Verify Test -- Fail -- Block 97822802 (31% -- different block): Timeout waiting for IRQ ..... Block 97822803 Timeout waiting for IRQ... Presumably 804 as well, etc...

(Reboot)

SMART Test -- Pass

SMART Long Self Test (2nd time) -- The self-test failed the read portion of the test (error code 0F00:075D)

Confidence Test (2nd time) -- Pass

SMART Short Self Test (2nd time) -- Fail -- Self-test failed the read portion of the test (error code 0F00:065D)

Device Quick Check (2nd time) -- Pass

Start unit command (2nd time) -- Pass

Stop unit command (2nd time) -- Pass

Read test (2nd time) -- [As expected] Block 97822848 (31%) Timeout waiting for IRQ to respond

It would seem there's a series of blocks that are beyond bad/corrupt to the point it's forcing the tests to effectively crash?
And in addition, it's having trouble reading data from the disk?  Is it possible there are two independent problems?

Anyway, to clarify, at present the machine works fine except for the grinding noises and the errors that are appearing when I run the tests.  But is it the beginning of the end?  How long can I expect my hard disk to last?  Anyone have tips for, in what would be a minor miracle, fixing the thing (aside from taking it to a technician -- I'd rather just replace it)?  Preferably, if you can also tell me what's going on with it (as opposed to just, "Time to buy a new one"), that would be ideal.

Thanks very much for any advice you can provide.

Patrick