Shouldn't be an issue. See, PSU's can be complicated. Often it's less a matter of how much Wattage it is rated at, but rather the quality of the unit. You see, power supplies have lines. The most important lines of these are the 12v lines. The better the power supply, the more Ampere's the line will put out, and the more stable the lines will be. Often a 600W+ PSU from a generic, el-cheapo brand will be insufficient for a situation, where a 400W+ PSU from a reliable brand such as Silverstone/Enhance (Same thing), Enermax, OCZ/PCP&C (Now the same thing), Zalman, or Corsair will be more than sufficient. Depending on your current brand of PSU, the 450w you have will be enough. But make sure, if you replace it, you get a good one. The PSU is the most critical, yet most over-looked component of any PC. You mess it up, and you risk blowing the rest of your gear up.
If you have a older graphics card put that into be safe as it would probably use less power, but generally that requirment is if your playing games that put a level of strain on the card and nearly all of the time the "suggested" amount is much higher than needed e.g: 8800 ultra only needs 163W where as the suggested is over 450w
ok i have the computer up and running i can get into the bios but when i put the vista disc in it loads then shuts down immediatly.
let me explain what a power supply does it converts Alternating Current to Direct Current. The reason this has to be done is because, the high voltage AC current needs to be converted to low voltage DC. While AC is able to be transported long distances without tremendous losses(you loose a lot of electricity if you carry DC over power lines) it's really unstable. On top of that it is at a very high voltage, though this voltage varies to a fair degree. Delicate electronic devices typically operate best at lower voltages and and they need STEADY VOLTAGES. Go too high and the electricity will surely damage the components in due time. Go too low and the component will be unreliable as it's not getting enough electricity. The ideal is to have a power supply which puts out 100% stable voltages, a the right voltage, at any given power draw. The reality is though that this won't happen. a power supply might deliver around 12.1V or 11.9V and then it will vary by .1V at a given interval, but the change will occur so rapidly most instruments won't be able to detect it. a thousandth of a second is an eternity as far as ICs are concerned however, you can fry a chip, or damage it quite easily in this time period. a cheap power supply might be .5V off the mark and then wobble by .5V. That's really bad. On a 12V rail that's nearly a 10% difference. or, a cheap power supply might deliver exactly what it supposed to... up until 100W load... after that it just struggles. There are "600W" power supplies out there that I wouldn't trust to my crappy backup systems.
There are some PSU's out there I wouldn't trust having within a metre of any power socket. I have had really bad experiences with PSU's taking whole systems out. That's why I'm skeptical when people say things like "Rosewill is a reliable brand."
haha, i got everything running fine, im actually posting from that pc now edit: now everytime i install the graphics card drivers it says "No ATI drivers installed or the ATI drivers are not funtioning properly. Please install the ati drivers appropriate for your hardware.