PSU Question - Connectors

Okay, I made a newbie mistake and bought a 8-pin CPU power mobo when my PSU is only a 4-pin.

Are there any problems with buying an adapter for that 4-pin PSU in converting it to an 8-pin? Or is that only possible for PCI-X?

Actually, I have a molex to 6-pin that I could use for my PCI-X graphics card (will it work?).

If I can replace one of the two PCI-X and insert it as the 8-pin to the CPU power, will THAT work?

The PSU doesn't come with a 4+4-pin.

In any case, does it matter where what wires go where? Does the PCI-X connectors HAVE to go to a PCI-X input?

NOTES:
CPU: Intel Core 2 Duo E8400
Motherboard: XFX nForce 780i SLI
Graphics: XFX GTX 260 Core 216 PCI-X
Power Supply: Xigmatek 650W