broadbandspeeds and computer speeds

I'm on a VM cable modem with a 10 Mbps package, with a home network. I have been experimenting with doing the test from different computers, of which my wife's is more recent, and presumably faster, than mine. I find that if I do the test on her computer I get a speed of about 9 Mbps, while on my computer I am getting about 6 at this time of day, with much poorer (2 or 3 Mbps) results in the evening in this terraced residential area. Would one normally expect the speed result to vary in this way with the speed of the computer? I assume the slower evening results are due to contention with other users.

Power of PCs doesn't really come into it.

But are they wired or wireless? If slow one is wireless, there's your answer.

In reply to a post by XRaySpeX:

Power of PCs doesn't really come into it.

But are they wired or wireless? If slow one is wireless, there's your answer.

Or perhaps different makes and models of wifi card.

As others say wired/wifi or brand of card ...

Or RWIN and MTU can affect it too.

What are the differences in spec for the interfaces and what application are you using to check the speed?