I used a jigsaw for all the cuttings in my case....I really wouldn't recommend it as it's extremely loud, and towards the end of the cut your case will want to shake REALLY bad, not only that, but chances are you will be left with a lot of burrs and pointy ends that you'll need to flatten or file down. The Dremel is the modders best friend and anyone who does extreme case modding will tell you so. If you don't have a dremel I suggest you pick that one up you linked to anyway as it'll help make finer edges and clean up whatever edges need it.
35,000 RPM spinning diamond carbide blade is supreme over a jagged jigsaw and either one would take you a while. You can see my case mod project here:
and that took 2 days of work, few hours on saturday, few on sunday and the few on sunday was finishing up holes, and then putting it all back together. Either way though, cutting through the case with the jigsaw was no faster or easier than a nice edged fast RPM dremel.