Você pode usar o conky para fazer isso.
Conky é um aplicativo que desenha uma sobreposição em sua área de trabalho, mostrando diferentes informações do sistema. Você pode personalizar o que é mostrado criando um arquivo ".conkyrc" em seu diretório pessoal.
Este é o arquivo .conkyrc que eu uso (É uma versão modificada da que está no PartedMagic):
# the list of variables has been removed from this file in favour
# of keeping the documentation more maintainable.
# Check http://conky.sf.net for an up-to-date-list.
# set to yes if you want Conky to be forked in the background
background yes
# X font when Xft is disabled, you can pick one with program xfontsel
#font 5x7
#font 6x10
font 7x13
#font 8x13
#font 9x15
#font *mintsmild.se*
#font -*-*-*-*-*-*-34-*-*-*-*-*-*-*
# Use Xft?
use_xft no
# Xft font when Xft is enabled
xftfont Bitstream Vera Sans Mono:size=11
# Text alpha when using Xft
xftalpha 0.8
# Print everything to stdout?
# out_to_console no
# Print everything to console?
# out_to_console no
# Update interval in seconds
update_interval 5.0
# This is the number of times Conky will update before quitting.
# Set to zero to run forever.
total_run_times 0
#own_window_title Parted Magic - conky
# Create own window instead of using desktop (required in nautilus)
own_window yes
# If own_window is yes, you may use type normal, desktop or override
own_window_type normal
# Use pseudo transparency with own_window?
own_window_transparent yes
# If own_window_transparent is set to no, you can set the background colour here
own_window_colour black
# If own_window is yes, these window manager hints may be used
own_window_hints undecorated,below,sticky,skip_taskbar,skip_pager
#own_window_hints below,skip_taskbar,skip_pager
# Use double buffering (reduces flicker, may not work for everyone)
double_buffer yes
# Minimum size of text area
minimum_size 280 5
# Draw shades?
draw_shades yes
# Draw outlines?
draw_outline no
# Draw borders around text
draw_borders no
# Draw borders around graphs
draw_graph_borders yes
# Stippled borders?
stippled_borders 4
# border margins
border_margin 4
# border width
border_width 1
# Default colors and also border colors
default_color white
default_shade_color black
default_outline_color black
# Text alignment, other possible values are commented
#alignment top_left
alignment top_right
#alignment bottom_left
#alignment bottom_right
#alignment none
# Gap between borders of screen and text
# same thing as passing -x at command line
gap_x 15
gap_y 15
# Subtract file system buffers from used memory?
no_buffers yes
# set to yes if you want all text to be in uppercase
uppercase no
# number of cpu samples to average
# set to 1 to disable averaging
cpu_avg_samples 2
# number of net samples to average
# set to 1 to disable averaging
net_avg_samples 2
# Force UTF8? note that UTF8 support required XFT
override_utf8_locale no
# Add spaces to keep things from moving about? This only affects certain objects.
use_spacer none
TEXT
${color goldenrod}Hostname: $nodename
${color goldenrod}Linux Kernel: $kernel
${color goldenrod}CPU Details: $machine, $freq(MHz)
${color}CPU History: ${color darkgreen}${cpugraph 30,0 0000ff 00ff00}
${color}CPU Usage:${color magenta2} $cpu% ${cpubar 11,0}
${color}RAM Usage:${color DeepSkyBlue1} $mem ($memperc%) ${membar 11,0}
${color}Available RAM:${color DeepSkyBlue1} $memmax
$color$stippled_hr
$alignc${color}Processes:$color $processes ${color grey}Running:$color $running_processes
$alignc${color}(top 5 sorted by CPU usage)
${color goldenrod} NAME PID CPU% MEM%
${color} ${top name 1} ${top pid 1} ${top cpu 1} ${top mem 1}
${color} ${top name 2} ${top pid 2} ${top cpu 2} ${top mem 2}
${color} ${top name 3} ${top pid 3} ${top cpu 3} ${top mem 3}
${color} ${top name 4} ${top pid 4} ${top cpu 4} ${top mem 4}
${color} ${top name 5} ${top pid 5} ${top cpu 5} ${top mem 5}
$alignc${color}(top 5 sorted by MEM usage)
${color goldenrod} NAME PID CPU% MEM%
${color} ${top_mem name 1} ${top_mem pid 1} ${top_mem cpu 1} ${top_mem mem 1}
${color} ${top_mem name 2} ${top_mem pid 2} ${top_mem cpu 2} ${top_mem mem 2}
${color} ${top_mem name 3} ${top_mem pid 3} ${top_mem cpu 3} ${top_mem mem 3}
${color} ${top_mem name 4} ${top_mem pid 4} ${top_mem cpu 4} ${top_mem mem 4}
${color} ${top_mem name 5} ${top_mem pid 5} ${top_mem cpu 5} ${top_mem mem 5}
$color$stippled_hr
$alignc${color}System Uptime:${color DarkOrange1} $uptime
${color} Battery: $battery_short ($battery_time) ${color grey} ${battery_bar 11,0}