Well if your going to start adding lights and extra fans stuff like that, yes get a new case or new power supply if you want to keep that case. If your going to attempt to do that kind of stuff go with a 431watt case gives you plenty of power.

Exactly.

i just got a new system adn the case that came with it is a AOpen KF45 Mid Tower (300w PSU)

am i goign to be able to mod this baby or should i go out and get a new case while im at it ?

so its realy just the power supply thats holding me back then? not so much the actual case?