Nice thing about the older Epoc netBook is that there is hardly any development on it now. Seriously, the epoc OS is indeed solid as a rock, and it has all the business apps I need, and as there no new ROMS I can get on and actually use it. Trouble with my Z is that I am forever tweaking something, breaking things, reinstalling things... its fun, but I can't let my business depend on it.
One thing both the Z and the trusty old netBook have in common is the amount of free software. Compared with Windows Mobile, or even my Epoc decended 'Symbian' mobile phone that is. Its nice that I am not having to spend any more money on them.
Oh, the old Epoc netBook has a 640x480 screen too. But as it is so much bigger physically, it is easier to read especially when doing long word processing and spreadsheets. The keyboard is very easy on the fingers too. Finally, even though my netBook is one of the older machines its original battery still outstrips any portable I own.
The one thing I have against the netBook is that both the main web browsers available for it are showing their age and having increasing difficulties with some websites.