This will also mean that I will be shipping to an address which my card is not registered to. Is this a problem in the states?
If they accept your UK card, it shouldn't be a problem at all. As long as your billing
address matches the address on your card, they should accept any shipping address. This is how you buy gifts online, remember.
As a side question... can anyone advise me on whether it is safe to put CPUs or memory through airport Xrays!
Shouldn't cause a problem. I work in a building with xray security at every entrance. My PDA, MP3 player, and cell phone go through every morning, without any issues.