I had the same problem in my old room - it was facing the east with windows running along the entire room. The temperature during the summer in there was around 90F, and the way the ventilation was set up was that the cold air actually pumped in to the room furthest from the hot windows. My desk was next to the windows, so it was incredibly warm (especially since I grew up in a lot colder climates than this ).

Don't underestimate how much a simple fan will help. I have one of the 18" desktop oscillating fans and it worked wonders.