I just got the wd 750gb black sata 3 drive. This thing is loud as heck. What wd drive in the sata 3 range is quiet? It has to be 7200 rpm though. And under 750gb...

There are no 3.5" (desktop) 7200rpm drives which can be said really quiet, and the ones which are not loud have not any noticeable performance edge over 5400rpm ones.
IMO.
You may short stroke some sub-6000rpm drive trying to achieve a decent trade off (I mean a 1Tb one such as the WD WD10EARS, the Hitachi 5K1000.B or 5K3000, or the Samsung F4)

If you want a sub 750Gb 7200rpm drive, I think that you should look at some 2.5" (notebook) model, such as the Seagate Momentus 7200.4 (but not the 750Gb), or the (somewhat less reliable) Momentus XT, or even the latest Hitachi.
Even a WD Scorpio Black can be enough quiet (so less quiet than the above quoted drives), but just when suspended and/or encapsulated, IME.
Unfortunately most of them aren't SATA3, AFAIK (but I don't see any need for SATA3, as any mechanical hard drive is just currently unable to saturate the SATA2 interface).

Last but not least, you may also give a look to a WD Velociraptor, but it's very expensive, and so I don't know if it's really preferable to a 256Gb SATA3 Crucial m4 SSD.

I got the WD Blue 320GB Sata 3 drive for $40 shipped from newegg. Its 7200 RPM 16MB cache and I have used the WD 320GB sata 2 Blue drives before and they are fast, and very very quiet. So I hope this one is too

Give us some feedback.

Just wondering why do you need a Sata III and 7200rpm drive? Not sure if its for your computer on your sig, but if it is and you already have an SSD, i would just go with 5400/5900 rpm drive, like WD Green Caviar, Samsung F4 or my favorite atm Hitachi 5k3000. As an alternative you could try a laptop drive, the I read good things about the WD Black Scorpio, the new one is 7200rpm 750gb 2.5 drive, but its not Sata III (atm the only sata III laptop drives are ssds), but i doubt its a quiet as 5400rpm drive, none of the black caviar i tested have been quiet drives.

I actually have the 500Gb and I've tested against the 320Gb and 750Gb brothers.
It's not quiet, and it's fairly louder than my Momentus 7200.4 (but a bit quieter than the SB 750Gb); it currently works in a suspended SQD and I can clearly hear it while seeking: probably it's too much noticeable for a silent peecee, but it's not obtrusive in that scenario.

At anyway, the OP already bought the Caviar Blue: if it's enough quiet for him, all is well that ends well. N'est ce pas?

As QfS said above, this drive is far from silent and in all honesty it's borderline whether you could even call it quiet.

So now you've read some bad things about it too

I should have read the reviews at Newegg on the 750GB drive. Almost all of them said while the drive is fast, its very loud. Figures usually I read the reviews before buying buy this time I was in a hurry and forgot too...