I think there is a confusion here.
TFT is a display technology, XGA is a display resolution technology. In other words, XGA defines the number of pixels, while TFT defines a certain manner of displaying pixels (and is hardware restricted on the max number of pixels available).
You can display an XGA resolution on a TFT screen, or on a CRT.
For the moment, S/U/XGA is capable of defining much greater resolutions than TFT is capable of displaying (anyone seen a 2048 x 1536 TFT screen ?). I think it will stay that way.
Now, there is palmtop called XDA, are you talking about that ? If so, you are asking for a choice between a palmtop and a laptop. Such a choice cannot possibly be counselled by people who do not have a clue what your requirements are, or what you intend to do with your purchase.
A laptop is much more powerful in many ways than a palmtop, but a palmtop can be very good for a few select applications and is much easier to transport.
Without more info on what you want to do, nobody can give you an informed opinion.
Pascal.