There are a few things you need to know, about Solid State Drives, before you upgrade your computer/laptop/netbook to this newest technology.
1. Do you have a SATA or IDE Controller?
Most drives are designed for SATA, though there are some IDE (aka: ATA and PATA) drives available also. To know which one you need, look inside your computer, or check out the specs/details of your laptop/netbook.
If you have a computer, open the case and locate your hard drive. Look at the wires on the back of your hard drive.
2. Internal vs. External
External drives are mostly for portable data, like a USB flash drive, so an internal drive is the best option for an SSD drive, so it can make your Operating System (Windows, Mac OSX, Linux) faster and more responsive.
The most common sizes are 32, 64, 128 and 256 Gigabytes (GB). The operating system will use about 10 GB of space, so make sure you leave enough free space for your applications, games, files and so on. I would recommend getting a minimum of 64 GB, and up to 128GB, unless you have a big budget.
Continued at source: SSDTechnologyForum.com