since i use urxvt without transparency i don't need wallpaper which was good reminder. instead of it i use prompt string.
changing prompt string in bash
PS1='myprompt_string'
i add this string to my ~/.bashrc
PS1='c2d notebook: \w> '
\w escape sequence prints current working directory.
all escape sequences you can find here
i hope i'll buy core2duo notebook this month.