But i don't know if the motherboard will be compatible with my case. Are all motherboards compatible with every case? Also my case is a gateway case, since i am planning on upgrading, instead of building a whole new computer.
It should, unless your system is the slim design (narrow width). If in doubt, get my linkworld case with 500w ps if your video card is low to mid range. You can upgrade it later. Check your gateway power supply for a 6 pin pci-e lead if you want to get a decent video card, such as the 7770. Those require a 450w minimum ps.