Quote: "Good news though that this PC which has a video card that only supports DirectX 8 will run programs that use DirectX 9"
I'm no expert but, as far as I know, due to backwards compatibility, you'll only have problems with programs which use DX9 features that your card doesn't support. Even then, I would expect the program to still run, but you just wouldn't see the DX9 effects.
If a program only uses commands that are also in DX8 then you don't have any problems.
Someone is sure to set me straight if this isn't the case!
TDK_Man