When it comes to the question of using an SSD, @hyperslug has a good answer with lots of information about SSD and 10K drives. When designing the storage solution, you need to make sure that your hardware matches your use case. Here's a break down of the potential options:
- Fastest read/write/seek times you can get on a drive.
- Limited number of write operations.
- High cost and low capacity right now.
- Full drive encryption has some problems (source, but do a Google search for more info)
- Faster than a normal hard drive, but slower than an SSD.
- Essentially unlimited number of writes.
- Better Dollar per GB ratio than SSD.
- Generally the loudest drive
Standard Hard Drive
- Slowest of the drives
- Best Dollar per GB ration
- Can be quieter and draw less power than a 10K drive
- Best for medium to long term storage.
So what do you pick? Well it depends. In most cases, an SSD as your boot drive will do the most to increase your start up time and general performance of the system. This can be done with a relatively small (read cheap) SSD. The problem is that if you get too small of an SSD, you have to place your programs on another drive. When you do this, you will loose many of the speed boost that an SSD can give you in the terms of application launch times. Once the application is in memory however, the program should be running from memory and not have to access the hard drive that much. If application launch times are important to you, then moving that information to an SSD may require a bigger (more expensive) SSD.
But what about your data? Where do you put that? Depending on the size, you may be forced to leave it on a spinning disk. If the files are relatively small, you can keep your current project on the SSD and move files off on and off the drive at the start and end of the project.
Finally, what about security? If someone steals the computer, they can simply plug the drive into another computer and pull all of the data off the drive. One method of protecting against this is whole drive encryption. This makes sure that when the attacker looks at the drive, all they see is pseudo-random noise. The problem is that this type of encryption is not suited for an standard SSD. I have heard of self encrypting SSD drives, but have not tried them out myself.
So bringing this all back together, here's my recommendation based off of what I think you need:
Start with an SSD. Get one big enough to put at least your OS and Programs on it. Make sure to have at least 10-20GB free so you don't constantly have to work in a constricted environment. Get a large standard hard drive and put all of your data on that drive. Use full drive encryption on the storage drive to protect your data.
Once you have the system built, use it for a month and reevaluate if you need more performance. If you feel you need more speed, without sacrificing security, get a 10K drive and use it as a scratch drive. Use that for another month and then reevaluate.
Assuming you need more power, find a self encrypting SSD and replace the 10K drive with it. If you need more than that, you'll have to start looking at some really expensive equipment that is outside of the scope of this answer.
It's important to remember that speed and security costs money. The trick is to find the balance that maximizes your buying power.
Hope this helps