Thanks to X5World, Jochen & ccfj1, I've managed to accomplish the following in the space of 2 hrs:

1. Correct my BM53 radio "Country area" to USA, allowing proper tuning frequencies
2. Locate & Download v27.1 and v31 files, and burn each to CD
2. Update NAV to v27.1, verify function
3. Update NAV to v31, implement perspective mode

I'm one guy just now!

I'd best leave well enough alone for today, knock wood!!!......well, maybe find & buy a copy of a newer NAVTEQ map DVD