okay so heres the deal.  i built my pc about 2 years ago, and its been great.  a couple of days ago, i was playing fallout 3 (ive already logged at least 65 hours into the game) and it blue screened on me.  it rebooted, and i though "well thats vista for you.  oh well".  i thought it might be the processing and graphics and what not for the game and stuff so i just dismissed it.  
well then i had a blue screen right in the middle of just surfing the net.  problem here was, after it blue screened....i had to hold down the power button to do a force shut down.  but then when i tried to power back on after waiting about 10 seconds, it would power on (activity light) but nothing on the screen.  if i waited about 60 seconds or so, i could power it up and it would boot back into windows.  however, after a few minutes, it would blue screen again and i would have the same problem as before.  have to wait a few minutes before it would power on COMPLETELY.  
so my first thought was the power supply.  i went to best buy (cuz troubleshooting components and having to pay shipping and RMAing and all that sucks) and bought a replacement psu.  550w thermaltake.    i took the old one out, put the new one in, and when i powered on i thought i was hearing more case fans this time...as in it was louder than usual.  so i was relieved for the moment, and then proceeded to download the new expansion pack for fallout 3.  i got it downloaded, installed, and i started playing.  about 2 minutes into the game...another blue screen....same power problem as before.
so what am i looking at here?  cpu failure?  mobo failure?  cpu fan failure?  ram failure?  the ram i have in my pc is relatively new and has been working since christmas so i doubt thats it.  any suggestions??  im hitting the wall here  
