Hmm, doesn't look like there's really anything fancy going on with that keyboard. Swapping it temporarily just to rule it out couldn't hurt, but I don't think that would really do anything for you.
As for that mouse, I actually have the same one and I wound up retiring it due to reception issues (I used to use it for my laptop, then when I found it to be unfit for that, we started using it for our HTPC, then ditched it when it couldn't even manage that). :/ The issues were similar to what you were experiencing. If you tried to use your leg as a mouse pad it wouldn't work. If you had it too close to the receiver it wouldn't work (on my laptop, it didn't work well if I used the rear USB ports; I had to plug it into the ones on the left side to get a somewhat decent signal). If you looked at it the wrong way it wouldn't work.
Based on my experiences with that alone, and the fact that you seem to be having the same problems, I'd probably just look into getting another one. I would probably recommend going with Logitech, though. My dad bought the Microsoft Wireless Desktop 6000 for his computer and, though the keyboard works very well, the mouse has many of the same issues that the 3000 has. Logitech, on the other hand, has always had very solid wireless technology. Just avoid Logitech's more expensive offerings, because it seems like the more they charge the worse of a job they do.
* Spectere glares at his babied but broken G5 mouse.
