How big a power supply do I need?

My power supply (4 years old) died in its sleep over the weekend. I have to get a new one and am curious as to how do I determine how many watts I need? I built this computer several years ago and put in a Thermaltake Silent Purepower 480W. It sounded good at the time, but was it overkill or not enough power? What should I be using and why?
Thank you.

Windows XP Home SP2
Asus A7n8X Deluxe
AMD XP 3200+
Asus V9950 Ultra 250 MB
1024 MB OCZ Ram
WD SATA 160 GB
2 NEC DVD burners
CPU & Case fans

 

The Termaltake power supply was not overkill, and probably good enough. For a replacement, look for something over 450w (500+w is better) with plenty of amps on the 12v rail. The amps should be listed on the box, the side of the PSU, or in the PSU's spec sheet. You're looking for 28+ amps. The higher the amps, the happier the PC will be.

hopperdave2000

BTW- I'm running a 350w on my PC and have been for over 2 years w/o any problems, probably because I have 32amps on the 12v....

 

OK...thanks for the advice. I'll look for a 500w with at least 28 amps.

 

I agree with Hopperdave. 450 W was OK and almost certainly still is. But with all things get the best you can afford.