How do immortals modernize?
One thing I think is really neat about HIGHLANDER but can't figure out is how the immortals (Connor, Duncan, Kell, Kate, etc.) have managed to adapt to the changing times so well and speak American English, wear American clothes, etc. That would be quite an ordeal, for a number of reasons.
It is hard for most people (and I consider the immortals "people") to adjust their lifestyles to new eras, for reasons both mental and psychological. My grandfather was born in 1927, and it took him about 10 years to become familiar with DVD technology. Now, multiply that experience over hundreds of years and you will conclude that immortals from the medieval era should be - at best - awkward or clueless about modern times and - at worst - paranoid, despairing lunatics who don't feel they fit in anywhere.
Of course, possessing eternal youth would spare one the mental degeneration that accompanies the aging process for normal humans, so learning new skills (and retaining old ones) would not be too much of a problem for the immortals. But there still would exist the tremendous psychological handicap of not truly recognizing the world anymore. Unless immortals kept in close contact with their own kind, they'd be terminally frustrated at their failure to keep the "old ways" alive in the culture.