I was kind of thinking along the same lines. In fact, that's where I got the boot.img you downloaded. I just extracted the rom.zip from the RUU and then pulled the IMG file out of it (we just rename it to PB31IMG so the Inc will recognize it in hboot). The oddity here though is that you're already flashing all those partitions when you run the RUU so we'd really be doing the same thing it seems to me.
The only thing I can see helping the situation right now is to get a working recovery that doesn't cause a boot loop. In order to achieve that, I think we need to fastboot flash it. But before that's possible, you need to run a 'Fastboot Devices' command to make sure your device is recognized. Earlier you said your device wasn't listed and if that's the case, we need to do some driver work potentially. You can fastboot flash all day and without the device being recognized, you're aren't going to get anywhere. So once we get the device recongized, we can try to proceed.
Also, you didn't answer the question I asked a few posts back...are you navigating to the SDK/Tools folder via command prompt before issuing the Fastboot commands? If not, it won't work either. Have you used the SDK on this computer before?