Hello everyone. This is my first thread as I am new to the forums. I recently bought a gateway dx 300 desktop for school. It has a ati 5450 graphics card. I believe it also it has a 300w power supply. I have a couple questions. 1. how can I tell if a graphics card will fit into my machine? 2. What is the best graphics card that will fit under 150-175 dollers without upgrading my psu? 3. Is the 5770 any good? Im new to modding computers so take it easy please ! lol thanks in advance