The 300 on newegg does not say it holds micro ATX motherboards, but the Antec web site says it does so ignore my warning above.
The 200 has two speed fans, the 300 has 3 speed fans. The 300 illusion includes the two front fans so go with it if you like it. The 300 illusion is the best value because of the extra fans.
Those PSUs are the minimum you can get if you will add a graphics card later. Without power your PC wont work. With a weak or poor quality power supply it will run poorly and do flakey things like lock up. A bad quality power supply can actually damage other components in your system. The power supply is not something you want to skimp on.