Estimating Workstation Specs

Anyone have any idea on how to make a rational estimate for CPU, RAM, Graphics for a workstation that must do the following?

System Requirements

This list contains the minimum requirements necessary for PBS TeacherLine courses. You may use higher versions of software or faster internet connections, if desired.

Internet access via a 56k modem
Internet Explorer or Netscape, version 6.0 or above, Firefox, or Safari
RealPlayer 8
Windows Media Player X
Flash 5 Player
Shockwave Player
Adobe Acrobat Reader
QuickTime
Java 1.4.2.

I mean, do I add up the individual memory requirements for each individual application? And what about graphics – which is the biggest hog in this bunch?