A few concept drawings of what I have in mind
Style #1: simple interface (emphasis on searching and ease of performing common actions)
Style #2: orthodox interface (commander like with toolbar, I like this one xD)
Style #3: balanced interface (I think it would be better with the left being a |installed software | build messages | tab-thingy).
Personally I think the first style is easier to use if your not familiar with what your doing, can you get more simple then 'search, click, click' with a big set of buttons?
The second I really like because I think it makes best use of space and presents the most important information quickly.
The third, I think is probably a better choice since it combines #1 and #2's ways of doing things into a fairly simple yet compact amount of space.
To be honest, I would kind of love docking / undocking elements and a very 'cool' look, like XFire or XMMS L&F with a Gimp or Designer style of operation but I think that would probably be a lot of work and a bit confusing to new people =/