An IDE does more than edit, compile, link and debug. There are a number of software engineering functions that an IDE handles quite well. For example, source code management, keeping track of changes and a documented history of editing. Another is project management for the lifecycle of a product, where the IDE can show tasks and assigned programmers (very handy if you have to track down what someone else is doing).

Granted an IDE isn't necessary in a one man shop, but as any organization grows there has to be a standardized way of doing things so continuity is preserved through employee turnover. An IDE serves well in this capacity.

Look at what Eclipse does. There's the usual edit, compile and link, but it also has plug ins for source code management tools, project tracking, documentation, even bug tracking.

To answer original poster Zafar's question, I'd suggest looking at the latest Eclipse "Europa" package along with GNUARM for ARM development. Can't beat the price (free, but you have to invest some time in it).
Jack Peacock