BOAC,
I would highly recommend a Nokia 6310i.
It has all the features you list, except the covered keyboard, and none of the bits you don't want.
I'm on my second one now (first one nicked). I think it's one of the best phones Nokia have ever made.
Performance any sound quality are fantastic, and the battery lasts approx 10-12 days on stby. (Nokia quote 16-17 days, but this is a bit optimistic.
They are not available in shops any more, but there are usually plenty of new or nearly new ones on E-Bay.
Nokia used to make a connectivity lead, which went from the phone to the serial port on your comp. This is probably also available on E-Bay
What's a "quad band" phone. I thought that there were only 3 frequency bands available