Since there have been many inquiries about whether Nevo will work with h55xx or can be downloaded separately, etc., I thought I'd post an email comment I received from the folks at Nevo. Hope this will answer some of your questions:
"Compaq/HP has decided not to include the Nevo software in the iPAQ 55xx series.
Instead they have put it in the new 22xx series.
To provide a little background. NEVO is an embedded solution that turns a hand held device into a sophisticated and easy to use home controller. As such it is built into the device at the time of manufacture. Most current PDAs, have an IrDA port which is not fully compatible with remote control CIR (Consumer IR) in light frequency, transmission intensity and angle of transmission. While using this port could be done for control, it leads to short transmission distances and narrow beam angles making it awkward to use the device. Also it has difficulty transmitting high frequency CIR used mostly by European Consumer Electronic manufacturers. So it is not a universal solution. Nevo's hardware + software solution addresses these problems by being designed into the PDA as part of its core capabilities."