How Much Memory do you Need?
I'm going to make this really simple by recommending a memory size for your system based on the operating system you run. Of course, you can get really scientific and try to base your decision on results found with monitoring software like Performance Monitor, as described in Chapter 5, "Performance Issues and Troubleshooting." But memory is now so inexpensive that it's not worth your time to do a mental cost/benefits analysis over 64 MB of memory when the difference between a 64 MB upgrade and a 128 MB upgrade is just a few bucks. Go all the way and reap the benefits of having a truly maxed-out system.
So here are my recommendations:
Windows 95 Users: 32 MB minimum, 64 MB is best, 128 MB if you are working with graphics or very large documents.
Windows 98 Users: 128 MB minimum, 256 MB is best.
Windows XP Users: 256 MB minimum, 384 MB is best, 512 MB if your system allows it and you are feeling extravagant.
So now that you have an idea of how much memory you need, you need to figure out how to upgrade your memory. There are memory modules and there are memory module slots on your motherboard. Most HP motherboards have two slots, but some have three. If you want 256 MB of memory in your system and you have two slots, then you need two 128 MB memory modules. Alternatively, you could buy just one 256 MB module (if your system supports large modules) and leave the second slot open for future expansion. There is a little bit of juggling to do when figuring out how to expand memory. In some cases, you might need to remove modules you already have.
To figure out how to juggle the memory in your system, you need to identify free slots, existing memory modules, and how much extra memory you need. There are some minor calculations, but you can do them in your head.
Note that on some early systems that run Windows 95, there is a caching problem that actually causes the system to run more slowly when more than 64 MB of memory is installed.