i have a 250w psu and im tryuing to upgrade to a 400 but i dont know which one too buy
List the specs of your system - first let's make sure that a 400 watt psu will indeed be enough.
If you are planning to upgrade other parts soon, tell us what you will be getting so you can buy a power supply with enough watts for your future configuration.
my specs are
a minitower pavilion a50n
asus motherboard 800 mhz front side bus
p4 2.6ghz with ht tech.
120 gb hdd
512 mb ddr sdram
im planing on buying
radeon x800 vid card
4x512 mb ddr sdram
i hope thats what you need
I'm not sure how much power you would need but I have found that Antec power supply's with Low Noise technology are very reliable and quiet. For that I highly recommend any Antec power supply.
Sorry for never responding to your thread. Antec psu's are great, and so far, Thermaltake's are really good too.
Get a 450 or 480 watt psu (unless you want even more).