HP have just (finally!?) made WM 5.0 upgrades available for the 2100, 2400 and 2700. Each upgrade is £26 + VAT & shipping,

http://www.ipaqchoice.com/Generic3.aspx?page=wm2005

The 4700 upgrade is expected 1st of March this year.

(Thanks to Tony Whitter for the heads-up)

Marcus