Any new CPU you buy today – the processor, not the system unit as in Pinoy tech jargon – is faster than what you can use for office work and Internet surfing. Memory is the main thing that can speed up these typical uses.
Many system builders sell machines with a paltry 128 MB of RAM. I’m appalled. That’s not even enough to hold Windows XP in memory. 256 will only hold an office program and a browser at a time. You need at least 512 to make full use of your modern computer, and give your processor enough to chew on. The good thing is that mainstream DDR memory pricing is dropping, to give way to higher end modules (DDR2) that are used for high-end machines, servers and enthusiasts.
When you upgrade your memory, you need to test it. It’s also good to test your system if there are any hidden defects. Normal usage may not hit the bad memory chips or cells on your DIMM (the memory module that sticks into your motherboard), or trigger the CPU or cache (high speed memory on your processor) conditions that will hit a failure. Burn memtest86 on a CD and run it overnight.
Consumer-grade memory is not like a hard drive that can detect and possibly recover from errors. If the operating system writes to a bad spot, it will get a bad value the next time it reads from it. The symptoms are if your PC just locks up hard, or if Windows crashes with a blue screen or an error message. High-end machines that cannot tolerate faults make use of memory modules that can do error correction (ECC), and motherboards that can shut down bad modules without shutting down the system.
Since your consumer PC can’t do that, the next best thing is to test it before it breaks.