Do i need a new PSU?

[BenW]

Im currently back on my old dell motherboard so i can't get any volt readings but when i was on my now broken gigabyte motherboard speedfan was reporting some very low voltages.

The strangest one was the -12V reading which was something like -9V!!!

The PSU is a 300W SilentX which i bought for its quietness and it is indeed very quiet.

Now my system specs are:
P4 2.26 (was running a 1.25V when i got those readings)
Gigabyte Motherboard
Radeon 9800Pro with ATI1
Samsung Spinpoint 160GB
Samsung CDRW/DVD Combo
Sounblaster Live 5.1
1 case fan

Think thats it, point out anything i've missed

[Steve]

-12V is always way out in my experience.