check out this site:
http://www.jscustompcs.com/power_supply/

I've got a LOT more then you & I ran ok on a 350. You'll be fine.

The reference number for the maximum wattage is strictly for advertising. The "combined" wattage is the rating of the +3.3 and + 5 and +12 volt lines together and is lower than the maximum wattage by a minimum of 20 volts which is reserved for standby power to the -5 volt and -12volt lines which aren't used anymore anyway.
The CURRENT ratings of each bus on the decal are what you need to look at. Some of the ampere ratings are much lower than others. Regardless of ampere and voltage ratings some power supplies do not supply steady voltage, a critical factor to good PC performance. The vaiations should not exceed + or - 5%. Some power supplies overload and cause overheating at the same time. Many have automatic fan controls that don't work so well especially if the PS overheats. Others allow you to control the fan speed manually. The better PS manufacturers today often employ a 120mm fan.
Some high end systems will occasionally spike the voltage to 300 or even 350 actual volts.
In addition to the above some of the PS are really noisy and many of them don't have enough power connectors forcing you to add on piggy back cables. There should be SIX at a minimum with additional case fan connectors.
Some good 350 - 400 watt PS are made by QTechnology, Fortron Source, and Be Quiet. Aerocool and Vantec are also good ones. If none of those are available Antec PS are also good.

John

If you add more hard drives (I have four), you'll definitely want a 400 watt power supply. Pick a good quiet one!

Check the January 05 issue of Maximum PC magazine. They did a torture test of PC Power Supplies.

Thanks guys....always can count on this forum.

Friar....cool site. That's a keeper.

If your handy with tools you can add two 300 watt supplies to your computer and slave one of them with a 12 volt Radio Shack relay and socket. You can't be a clutz do to this however, but it does work well.

JJK