Recently, my heatsink managed to fail (that is, I'm pretty sure it did - my BIOS is telling me something along the lines of 'chip fan failure', and I get a nasty grinding noise from it).
A heatsink is a solid piece of metal -- unlikely to fail. The fan, however, has probably busted a bearing or something. When the BIOS calls it a "failure" it's just a scary way of saying it isn't spinning. Anyways, now that we have that technical stuff out of the way...

I'm going to get myself a new one tomorrow, but I'm going to check first; anyone know of decent brands to go for?
You can't go wrong with a Zalman CNPS7700. It's big, it's made of copper, and it's extremely quiet for two reasons. First, it uses a huge 120mm fan, which means it doesn't have to spin as fast as the traditional CPU fan to move an equivalent quantity of air. Second, the heatsink is so big that the fan barely has to do any work at all -- depending on how hot the chip is and what you're making it do, the thing can range from a faint hum to almost completely silent. Even with all this sound reduction in place, your chip will probably run colder than it did with the stock cooler.

Ah yeah, another techie friend I was talking with swears by the Zalman fans, too. Of course, at the time I was looking at a mobo that wasn't compatible with them, but seeing as I don't have enough money to do jack right now (now kinda waiting for Gems Collection, Twilight Princess, MMX Collection, HL2: Aftermath...), THAT can be easily amended.

Anyway, yeah, I'm getting the impression the Zalman fan's what you want, but make sure your mobo is compatible in the offchance it isn't.

If it's an Athlon 64 mobo, then it has either a Socket 754 or 939, both of which the heatsink will fit into.

Oh yeah, when you go to install the thing, remember to thoroughly clean the surface of the processor with alcohol to remove any excess thermal interface material. Then add new paste and screw it in.

I also recommend Arctic Alumina or Arctic Silver thermal grease to fill any microscopic air gaps. Those thermal pads that come on the bottom of heatsinks I usually scrape off and replace with Arctic Alumina. This is just my habit, those thermal pads work just fine, they compress to fill the gaps.

Jimro

can they support athlon xps?

Thanks all. My mobo does indeed give enough clearance for the fan to fit in, so that's not a problem.

Koolkaz - It seems that particular fan won't go on an Athlon XP because those are little Socket A/754s, and apparently the sheer size and weight of the thing would damage the chip.

The mobo I'd been looking at matched both those specs (Athlon 64 and Socket 939) but Zalman STILL put it in the "incompatible" category.

Regardless, it was mATX anyway, so I'm looking at other mobos right now. I mean, not like I can afford anything yet, so what's the harm in changing my mind on a few parts?

Well, if you ask me it's best to spend a bit more on something you'll use longer than to get a cheaper component and end up upgrading it in less than six months. It took me ages between deciding what components I wanted and actually buying them and building the thing, though I think it was definitely worth it. Heatsink fan excluded.