Dude... It TOTALLY depends on what you want to use your case for, and what kind of cooling you need. The case has plenty of room for a duct, so you can easily use very powerful fans, andoerclock a bit if that's what you need. No need to spend £50 on a new case if what you have will do the job, and you're happy with it.
It all comes down to airflow for component cooling. You have to remember a couple of things:
1) Air moves where it's EASY to move to. So while small holes in the case will draw some air (screwholes, USB ports and the likes), then it's not a lot compared to the dedicated "holes" where you place a chasis fan, or have a major outlet/intake.
2) You dont need more than one or two chasis fans, TOPS, if you cool your components correctly. In fact, if you dont OC, the PSU fan is usually enough for memory and HDD
3) Major components that need cooling are: CPU, GPU, HDD, northbridge, any high voltage converter, and if you OC, sometimes your memory.
4) Get a thermal image of your PC while running if you have doubts about what gets hot.
5) Use cableeater and round cables to minimize the "bloackage". Add pieces of cardboard to force air to move through certain paths in your case (not nice to look at with a window, but it'll work with anything that looks fancy also).
A DIY cooling is not that hard, a little tape and come plastic parts and you're good to go. I use velcro myself, but that's because I move stuff around in my casing a LOT, and I dont like to get sticky fingers from working with tape I need to remove in a couple of weeks anyway.
