wacom cintiq and other digital sketching tablets

i’ve been using my trusty ol’ acer travelmate tabletpc for sketching for a couple of years now but it’s starting to show it’s age. i was wondering if it is worth spending the extra money on a wacom cintiq for sketching, i mean, i love sketching and it’s a critical part of my process but those cintiqs are expensive ?! is there much of a difference between the tabletpc and cintiq when it comes to sketching ? are there any equally good alternatives to the cintiq ? does it make a difference if the device has a wacom digitizer built in (i don’t think my travelmate has that) ? does anybody know of any places in new york city where i can try out cintiqs or other tablets/tablet pc’s ? thanks for your help…