After a quick look I did not find a version of Frontpage or NVU that would work on a PDA. But I could suggest you to build an empty template of a web page at home and just fill it on the road.
If your intention is to build fancy webpage then go for a laptop but for me I like my PDA for mainly writing my adventure (this is what takes time). Then you just go to an internet cafe and after it's only a matter of a few Cut and Paste to build your webpage.
As for typing on a PDA: Now a lot of them are equiped with bluetooth technology so you can use a compact wireless keyboard. I would suggest you to buy one if you go that route (it weights about 150grams).
I can say that the prices of Laptops are a lot cheaper now than 2 years ago when I left for my trip. But I still like my PDA: it's really small and light, it fit very well in a compact waterproof plastic box inside my panier. Also the battery life is more then 8 hours and in case it get stolen, it's less money to lose.