I need to replace my 5 year old Dell. It's slow, cracked and noisy. Probably the fan is clogged up with shite of various kinds.
Does anyone have any experience of Dell Precision vs Thinkpad W510 vs HP Elitebook in terms of quietness? The trouble is that they all have quite power hungry graphics cards so I would expect them to produce a lot of heat and therefore have loud fans. I've read that the Thinkpad has the most efficient cooling layout but some actual user feedback would be good.
On site the noise doesn't matter but in my office at home it does!

I can't advise you on this kind of laptop but since no one answered...

Do you have a good reason to want such graphic cards? It's not the first thing I'd worry about.
The W510 has a 16:9 screen for instance. I don't know about you but that's not what I consider a "workstation" display regardless of how it's marketed. You'd have a laptop that's much wider than the keyboard. 15'' 16:10 displays are bad enough! Thinkpads with integrated graphics can be quiet but I haven't tried a Thinkpad with dedicated graphics since the T60 which was very noisy and overheated. But some Thinkpads have switchable graphics which should let you have a quiet laptop when you don't need dedicated graphics and a capable one when you do. I don't think the W510 is one of them: the previous generation had that feature and they also had good 16:10 WSXGA+ 15'' screens (yes, that particular panel is better than the others). And if you want a Thinkpad with a 4:3 display, the latest such model would probably be a 14'' T61 featuring a Penryn.
HP makes nice laptops as well obviously. But by comparing the most expensive current model from both brands, you may miss something which would suit you better...

I'm not surprised there's been no answers yet. This forum is only marginally more popular than the watercooling and networking forums.
Still, I did think that there might be some engineering types out there who have notebooks of this type, who haven't lost some of their hearing and who could give me some feedback. I obviously work with people that use these machines but the environment is too noisy to be able to assess how noisy their laptops might be. And I'm not about to invite someone I barely know back to my hotel room so that I can listen to their computer. Geekiness is very much frowned upon in my profession.

Graphics card is for CAD. Whether or not I need the extra power of the Quadro FX 880M that's found in the workstation class laptops as opposed to the NVS 3100M found in the Thinkpad T510 and Dell latitude, for instance; I don't know. There is quite a jump in performance but that comes at a cost of around £200 and a larger power brick. You might well be right in saying that something like a T510 would be better than a W510 and it also comes with switchable optimus graphics.

As far as the display goes, 16:9 is garbage unless it's for watching movies but the fact is, as you say, that's pretty much all that's available on a new 15" laptop. I would love to be able to get something with a good quality 4:3 screen with a resolution of 1600 x 1200. A 17" @ 1920 x 1200 would be nice but would also be too big and heavy.

The other reason for going for a workstation class machine is of course the build quality. I take my laptop on site with me and it needs to be robust and durable but not to the extent that I would consider getting a Panasonic Toughbook - they are very expensive.

I don't think the T510 has switchable graphics like the T500. The T500 is 16:10 while the T510 is 16:9. Though 14'' 16:10 is saner if you ask me.
If you need the latest graphic cards, then you've gotta live with the insane aspect ratios but I'd much rather use an older laptop. I figured you could live with an older laptop as well since you were upgrading from a single-core Penitum M (the Core Duos were released less than 5 years ago, right?).

Maybe HP has a "workstation" line that's better built than its premium business line but so far as I know W-series aren't built any better than T-series. The relatively cheap T61 are great while the expensive T42p and T43p with IPS screens which I guess used to be IBM's "workstations" back in the bay were horrible when it came to build quality. Great UXGA displays though.

It is actually a T2500 2 GHz Core Duo, from early 2006 so when I said 5 years old, I should have said almost 5 years old.
I wouldn't replace my old laptop with another old laptop - I reckon 4 - 5 years is a good enough lifespan and I can justify buying a new one... cost wise that works out at about £4 a week, which in the UK would get you about 15 cigarettes.
I also think that buying in January might mean that I can pick up a good deal on a current model as apparently "Sandy Bridge" is coming out... so presumably manufacturers will be wanting to get rid of "obsolete" stock.