Got it working with the UK maps, thanks everyone for continuously keeping this thread up to date. Longest part was backing up everything.
I loaded the UK 2008.07 UK maps, poi and buildings and 2008.01 WestEUMAJOR ones as well. I left all of my US maps on there, I imagine this may affect the boot time, but I'm not too worried about it. As long as they all fit, I figured I was ok.
One question, what are the FYROM8_2008.07 maps? I noticed them in the Europe downloads, but haven't been able to figure out what they're for.