Looking for a new drive for my OS, games installed on Samsung 500GB Spinpoint.
Is it worth investing in a 150GB Raptor or should I choose something bigger in the 7200rpm range?

Yes, the Raptor is still worth it.
Solid state drives will take over in the future.
You will get better access time with the Raptor over a regular 7200 rpm drive.

depends on what you are going to do with a raptor.

In games, loading times will be a little faster (not a whole lot though) and framerate will be unaffected. Boot times should decrease a bit, and apps that are read/write intensive will see a very good boost.

Another consideration is noise. If you are one of those people who can't tolerate any noise coming out of their computer, you should look elsewhere, as raptors can be noisy at times.

If you have plenty of cash, go for it, but if you are trying to save money, this may be one of the better places to make a sacrifice, unless you know you will be running read/write intensive apps.

I do have a couple raptors in my build, but I could afford them, so it wasn't an issue. If my budget had been reduced, they would have been one of the first things changed on my list.

First, what do you expect/think the raptor will do?

Second, are you buying the raptor at the expense of something else? If everything else in your system is near the top of the line, then get the raptor. If however you are using a low end dual core, or a 7900GS or less, you have other upgrades to do.

System

Quadcore Q6700
BFG 8800 GTX OC
4GB Crucial Ballistix
Gigabyte N680SLI-6DQ
Creative Fatal1ty Pro

So fairly near top of the range.
Guess its gonna be the Raptor then (just for the OS, its only money!)

Another vote for worth it - if you don't need a lot of disk space.

I think it's about time that WD released a 300GB PMR Raptor.

In a word: NO

From a post earlier today:

Edit: This is quoted from me, I simply didn't feel like retyping it.

Yup, but its like Nvidia milking the 8800's because it has no competition at the top end. Until another HD company releases a Raptor trouncing 10,000RPM HD, Raptors are going to be overpriced and small storage.

True, but the Raptor is in the process of being dethroned. They had better get on the ball.

it depends what program you will use, for store large file, go get 500Gb.
for speed, raptor is the first choice.
I install my os in raptor, 500GB samsung for movie. The top two pc upgrades for me are 2Gb ram and Raptor HD in last year.

I am a Raptor Owner.

Noisy? Yes.

I have removed the HD from the computer and ran the drive. It still shakes, rattles and rolls. CPUS's constantly write to the OS drive, so the raptor can be heard bumping and clicking every few seconds.

Is it fast? Oh my yes. But I think the noise levels negate any speed benefits.

I will be replacing the Raptor with something equally fast (and quite) reaches the market.

Would I drop down to a slower, quieter HD? Most likely not. But I would understand those that did make such a move.

If $ was tight, I would skip the raptor all together.

If this is your system, I have no problem suggesting a raptor. I get annoyed when people talk about buying raptors, AID0 setups, soundcards, etc when their CPU is an Intel <=4xxx and their video card is a 7600/8600GT or a 7900GS. The raptor will decrease the load time for your games/boot windows. (if you are like me, you never shut down, so that last one is something I don't care about.) You should be seeing good frame rates in your games, so anything that will decrease load times would be your next concern.

As Kyle pointed out, you can also consider setting up an AID0 setup. While I do suggest a Raptor for your OS drive, I never suggest an AID0 setup for your OS. There is simply to great a chance of your RAID driver getting corrupted and needing you to reload EVERYTHING. You could setup an AID0 setup and put the windows swap file on it, as well as your video games. You should still see a lot of improvement, and if your AID0 dies, reloading isn't so bad.

I in no way suggested to the OP to go RAID. I never suggest that. I'm anti-RAID (on any reasonable budget).

I was simply stating that read/write rates of high-density drives make the Raptor look like a really silly idea (cost, size, noise, power consumption, etc).

Most get the Raptor for the OS and applications.
Then a larger drive for data. The data drive doesn't need to be as fast.
I forget how fast the Raptor is until I boot off another hard-drive.