Increasing your computer's random access memory (RAM) is one of the easiest do-it-yourself hardware projects. You can upgrade to 4GB or even 8GB starting at prices less than $50. Performance improvement will be most noticeable if you are the type of person who keeps several programs running at once, or who works on RAM-intensive projects like video or image editing. But improvement might be modest if you are not a power-user or you already had a decent amount of RAM (4GB or more). Still, even a slight improvement might be worth the cost. After installation, you should notice applications and windows opening faster and fewer instances of the annoying hourglass or rainbow wheel "wait" icons.
RAM comes in multiple types and speeds and you have to select the variety supported by your motherboard. Common types are DDR, DDR2 and DDR3. Installing the wrong type can cause issues like corrupt files, which could cripple your system, so make sure to read your owner's manual or visit your computer manufacturer's site to determine what type of RAM you need for your model. You will also need to look into its maximum supported capacity (or number of gigabytes it can handle) and only install up to that amount. You can check your computer's system properties to determine how much is installed currently, though where to go for this information varies by operating system. On some operating systems, this will also show the type of RAM that the computer needs.
Installing RAM is usually just a matter of opening your computer case with a screwdriver, finding the RAM slots, unclipping any existing RAM that you're replacing, and inserting new RAM chips. Many motherboards require that you install pairs of RAM chips of the same capacity in certain sockets, meaning you might not be able to add just one larger chip. Also, you should test thoroughly right after installation to catch issues early, and check to make sure the amount of RAM you installed now shows up when you check your system properties. Afterward, you should notice fewer system slow-downs, and feel a little less like a hardware novice.