Please Help Sound Problem

Hello, I recently installed a NVIDIA GTS 250 on my Dell PC and also changed from a 375 to a 600 wat power supply.

Once re-plugging my computer in it tells me on my sound blaster there is no device installed. So i re-install my sound card with the soundblaster CD and fiddle with updateing drivers etc. After playing with certain settings like driver updates my sound will work fine and register my sound blaster. However once i shut down my computer and turn it on the sound is gone again. My pc says the drivers are working fine and my pc is even showing the sound blaster card as being there. I know its not a problem with the speakers because i get them working, i just cant understand why when i shut down its like i never fixed it. I am trying to do everything i can before a re-instalation of my windows XP. My sound card plugs and video card are all plugged in fine. I think the problem is a finer detail which i cannot seem to figure out. Any help with this would be greatly appreciated as i have exhausted hours into trying to find a solution however always end up back at step one. Any help would be great, Thanks!!