Yeah I've been trying to keep the RAM in my 4705 as free as possible so that I can use the bluetooth headphones. Some apps and utils just don't want to install anywhere but Ram though.
Hp's keyboard drivers for example. My current install method is first try SD, when that doesn't work try Ipaq file store, then finally RAM.
BTW I have a 1G SD and a 4G Microdrive in mine. Very sweet for carrying a bunch of music plus at least one Divx movie to play with BetaPlayer.