Pre-installation planning will pay off with happier users and time savings for you. Because it is so easy to pop in the CD or DVD and click through to install the product, it is equally easy to forego the planning process—but resist the temptation!
Your planning will involve several functions, including the funding source, network group, and infrastructure (hardware/operating systems group). The funding source or business group needs to tell you something about the dollars available and the planning period that this configuration should support. Are you building something to last for four months or two years? The business people will also have some requirements related to uptime and scalability. Incremental uptime and scalability is always more expensive as your tolerance for problems decreases. The infrastructure group will be able to advise you about your company's configuration rules, hardware-vendor recommendations, and approved levels of software. Don't forget about support as well.
Let's drill into some of the details.
If you are in a growing organization, you should probably buy bigger and more than you think you need. More memory and faster or more processors are almost always preferable. At the very least, ensure that you have room to grow. For instance, if you have four memory slots and plan on buying 4GB of memory, do not buy four 1GB sticks of memory, because you will have used up all of the slots. Instead, consider ...