Let be a lesson. Next time, Build your own computer.. Ok? its pointless to go to the store. Buy a computer, and then end up changing out the parts because in the long run you've spent more money and still can't get your rig as far as you want to because its held back...
Just get a I5 2400, 450 watt PSU, and a GTX 650 or a 7750 (AMD). 6GB of ram is plenty enough.. unless you want to get a 2x4GB (8GB) kit. Once you have all that. 1.Remove the side panel from the tower.
2.Remove the computer's power supply by uplugging all the connectors and unsrewing the 4 phillips screws. Vice versa with the new power supply. make sure the power supply isn't connected to a Wall outlet any anytime until this entire process is over.
3. take the watch battery looking thing and take it out. Put it back in after 30 mins (this process is known as clearing the CMOS)
4., then take the CPU heatsink out then carely take your Pentium CPU out (recommend reading or watching a video on installing Intel CPU) and insert the I5 without breaking any pins. then return the heatsink to its position.
5.Take out the RAM that comes with your computer. And insert the new sticks properly. Next
6.insert the graphics card of your choosing into the long slow on the motherboard (PCI-e X16) now
7.make sure everything that needs to be connected to the power supply is connected.
8. Screw the screws in tightly.
9.Slide the side panel BACK ON. and
10.plug the new power supply up to the wall out. Flip the switch.