This isn't a simple yes or no answer. While the power and storage capacity of present servers greatly outstrips those of days gone by, the true answer still remains "it depends." While Win2k is more efficient and more stable than NT, it still comes down to system design.
Whether to specialize servers or consolidate will depend on the applications to be be run and the number of users that will access these applications.
Many applications by default will use all available CPU cycles and memory as a normal means of operation. Putting several such applications on a single server could lead to problems.
Putting several applications with large user bases on a single server can lead to I/O bottlenecks (depending on the storage technology used).
You need to look at the following before making any decision:
How many users will be accessing a given application?
How does the application use system resources?
What is the size of the files the application manipulates?
Hope this helps.