E900 sucks, touch screen sucks on it, they havn't made it quite so special yet, they need to make it better as you can still sometimes slip through menu's you dont want to go in.
K800i is a really good phone, i have it myself althoguh i must say that the joy stick on it is getting worse and worse.
Wish i had kept with the w810i because on that there is no joy stick and i know fixing a joy stick on a k800i isnt going to be cheap.
Although i must say, feature wise the k800i is pretty good. 3 mega pixel camera, bluetooth remote control, putting games on them is pretty simple too.
Maybe im just biased as i have one myself, but its upto you.
Woul'dnt sugest getting a samsung at all though, i find the phones very boring and not equiped with enough...
But yea, its upto you.
/Tofas