I've got TiVo Desktop 2.3a installed, and have no trouble transferring recorded programs from the TiVo Series 2 (40 hour) to my computer. TiVo and computer are both on wired (not wireless) Ethernet.
However, my computer only sometimes shows up at the bottom of the Now Playing list. Most of the time it doesn't show up.
TiVo Server is running (at least it says it is - when I hover over the icon in the system tray it says "Server On").