The original battery installed in my Palm Tunsten T5 is Samsung SDI PGF523759A (3.7V, 53x33x4 mm). The replacement I've googled is CS-PMT5SL (Part No. IA1XA27F1, 63x34x4 mm). Unfortunately, it wasn't in stock anywhere around.
The touchpad driver for Windows 7 on the official Asus site doesn't work properly: the grey icon in the system tray doesn't react on cursor movements and pressing of the buttons. The problem gets worse if KB Filter Utility is installed and you've pressed the Touchpad On/Off button. In such a case, the touchpad turns off and it's impossible to turn it on again until you uninstall Synaptics Touchpad drivers or KB Filter Utility (ATK, functional keys utility).