I hope I'm not going to spoil your Christmas with this post, but one thing I didn't mention above (because it's a common problem to all original D1's) is Microdrive compatibility.
The IBM Microdrive (in any of its versions) was never officially certified by Nikon for use with the original D1, and there have been quite a few reports of people having problems with them. I don't have any direct experience here since I've always used Compact Flash cards, but I'd recommend you take a look at http://www.robgalbraith.com/diginews/2000-11/2000_11_01_microdrive.html before you buy.
Incidentally, it's not necessary to go for the very expensive Lexar cards unless you really want the performance they offer: other manufacturers cards can be a lot cheaper and not that much slower. You might also prefer to use several lower capacity cards as a safety measure: if you were unlucky enough to get an error on one of them (very unlikely, BTW) then you wouldn't loose all your photos.
In relation to the speed of CF cards, it's possible to get round the fact that the D1 forces you to wait for your shot to be written to the card when in S (single frame) mode: if you put the camera into C (continuous) mode and set custom function 26 (which sets the maximum number of shots) to 1 then the camera will be ready to shoot again immediately unless you manage to fill the buffer. The only snag with this trick is you have to remember not to switch the camera off until it's finished writing the buffer to the card - or you lose any unwritten shots.
Perhaps I ought to put together a "D1 Tricks and Tips" post.