Dell is the Britney Spears of PSUs.
I am running the following on a stock Dell 250w(the Britney Spears of PSUs):
P4 2.4GHz
640MB DDR SDRAM
GeForce 4 MX 420
2x 7200RPM 60GB Western Digital HDs
PCTV Pro
48x24x48x CD-RW
50x CD-ROM
System is stable even with both CD drives going, distributed.net running(I crack RC5-72 for OCAU), and HDTV open(nothing overclocked).
Voltages(measured with a radioshack DMM):
12v: 12.06
5v: 4.99
3.3v: 3.30
BTW, I reverse engineered an old dell supply from a p133.
That dell supply used a LITEON power transformer(at first, I thought they only made CD-ROM drives).
There is only one switching transistor(well, only one big primary transistor, as there is a smaller transistor in the 5VFP supply, and several big transistors on the secondary side), but it is a high-power IGBT boobie(20A, 900v) in a TO-3 case.
The primary caps are 680uF each, for a total of 1360uF(most PC power supplies have only 2 470uF, or 940uF total)!