Help!I’m building my first computer and im looking for some suggestions. I need some ideas for a good case for under $100. Something with filters or screens would be nice because my room is dusty.

I am using a Biostar TForce6100-939 NVIDIA Socket 939 Motherboard and an AMD Athlon 64 X2 4400+. With that processer should I buy the regular windows pro SP2 or should I get Windows pro x64 or something else all together? Any other suggestions at all please feel free.