Another option, if your case isn't particularly cable management-friendly, is to bust out a drill and order a Nibbler metal cutter from FrozenCPU. Or you can use a Dremel if you're familiar with working with one (I like the Nibbler b/c I suck at making clean, straight cuts with a Dremel). Make sure to measure how much space your case has in between the motherboard tray and the side panel.
But above all else, keep your expectation realistic. The cases you see on this forum, as well as those on Xtreme Systems and [H]ard Forum, represent highly experienced people with lots of time, skill, and tools on their hands. Remember that all you see in the pics is the end result, not the 5-20 hours some guys have spent on post-assembly detail work. In addition to some very high-end cases designed for enthusiasts. And for a lot of folks, calling them enthusiasts is like calling a crackhead an "afficionado".
In the end, it's all a matter of what you're willing to do, how much time you spend learning, fiddling, obsessing, and squeezing. If you really want to learn how to cut a case all to hell, pick up an el cheapo case from Newegg with your next order and play around with it. Populate it with your old parts--might end up with a backup system out of the deal. Once you're done learning to cut the interior, learn how to cut extra fan holes. Then learn case paining. And so on.
There's my rant. My advice: if you can get good airflow and temps, be happy. Everything else is icing.