For VARs and systems integrators approaching operating system upgrade and hardware refresh projects, I think it's most useful to divide a customer's hardware needs into two distinct areas: systems that require multitasking capabilities and systems requiring a pleasant user experience, or unusually demanding graphics application.
Memory: The most critical component for multitasking
Demanding business users are true multitaskers, with multiple programs running at a time, large spreadsheets, active databases and big personal information managers like Outlook running. In this environment, you really can't have too much memory. RAM is plentiful in inventories around the world and that makes it cheap; with inexpensive components and hardware supporting massive amounts of RAM, there seems little reason to skimp on RAM for a new machine. As I've written before about Windows Vista hardware, the operating system can essentially use everything you throw at it.
Minimum spend: Spend as little as $200 on a new 1 GB stick of memory per customer machine and it will probably be the best money spent in terms of performance payback. Your clients will instantly notice a difference in productivity when they no longer have to wait for applications to option, tasks to switch, and drives to swap information to and from memory. Even if they already have 512 MB, I think they will thank you for the upgrade.
Video card: The most critical component for user experience and graphics potential
A substantial part of Windows Vista's revisions to the user interface appear in the introduction of a new theme, called Windows Vista Aero (or Aero Glass, as you may know it). Aero Glass is more processor-intensive and graphics unit-intensive than previous UI themes, such as the Windows 2000 or Windows XP default theme. Glass supports new features like transparency, 3D switching of open windows, full-motion video in thumbnails, and other niceties. There are a lot of myths, however, about exactly how demanding the new theme is. The truth is that it's not that demanding, but you will need more than a budget system to get the full effect of Aero Glass. There are valid business reasons for choosing Aero Glassm -- the UI improvements like 3-D window switching and thumbnail previews can save a total of a few minutes per day, which can pay back in terms of time saved surprisingly quickly.
Minimum spend: You need a card with 128 MB of RAM to run Aero comfortably with more than just a lightweight application or two running. Spend about $150 on a new video card to upgrade systems to Vista-readiness for Aero Glass; spend $200 to have a card that will run well in 3D animation contexts, computer-aided design and engineering applications.
Overall hardware considerations
If you've purchased a computer within the last two years, chances are you can spend a couple hundred dollars and upgrade the part of the system that will end up mattering most and get a very satisfactory return on investment. If customers are in the market for new computers, there's little reason to spend more than $800 to $850, given the prices of processors and components as assembled into full machines, on a system designed just for business use. Gamers, designers and others who need great video capabilities might want to up their realistic maximum to $1,500.
The bottom line? With Vista, $200 goes a long way.
About the author: Jonathan Hassell is an author, consultant and speaker residing in Charlotte, North Carolina. Jonathan's books include RADIUS, Learning Windows Server 2003, Hardening Windows and most recently Windows Vista: Beyond the Manual. His work is seen regularly in popular periodicals such as Windows IT Pro Magazine, SecurityFocus, PC Pro and Microsoft TechNet Magazine. He speaks around the world on topics including Windows administration, networking and security.