Pocketpcthoughts informs us that HP has silently changed that as their site now shows a new hx2190 and hx2490, each with 64MB RAM and 192MB ROM.

HP adds more ROM memory to iPAQ hx2000 Series

Back in September 2005, HP discontinued their old hx2000 series in favour of a new one based on Windows Mobile 5.0. Each model number was appropriately updated from hx2110, hx2410, and hx2750 to hx2190, hx2490, and hx2790 respectively. While the hx2790 was lucky enough to receive a wealthy memory configuration of 64MB RAM and 192MB ROM, the hx2190 and hx2490 had to settle for a lesser offering of 64MB RAM and 128MB ROM.

Source : pocketpcthoughts.com.