Only Chinese, Japanese and Korea version Windows ME has this issue, this is Creative SoundBlaster PCI 128 new multi-language version audio driver issue, we have been passed to Creative Inc, TUCD Ver.2.01 will modify this issue. You can manual install Creative CT5880 audio driver from driver CD's "Audio\CT5880\Audio\English\Drivers\Wdmdrv" folder, find "sbsetup.exe" file and click it, it will install audio driver.
The 20-pin connector belongs to older ATX standard while 24-pin connector follows newer ATX standard. The 24-pin connector just the 20-pin cable with 4 extra wires to provide extra current. As long as your power supply can provide sufficient power to the motherboard, you can still use 20-pin power supply.