i am using dell inspiron 640m laptop with debian. however during installation it said i had to recompile th kernel in order the kernel with some parameters . i have no idea what this means . the debian version is debian Sarge 3.1r0a.
Can someone tell how to get battery monitoring service running on the laptop. please help me.

1) You have to click with Right button on the pannel and select "Add to panel". Then just add to panel "Battery charge monitor" and you will see your battery status.

2) Go to the Desktop -> Preferences -> Power management -> General -> and select there "Always display icon" for example

If you will decide to save the power of battery, it is really good idea to setup it during compiling your own kernel:

'Power management options (ACPI, APM) -> ACPI Support -> and select there everything you want to support (AC Adapter, Battery, Button, Video, Fan, Processor -> Thermal zone)

& also

(This setup will really help to save power of the battery because it will automatically scale frequency dependable on your usage of CPU)
Power management options (ACPI, APM) -> CPU Frequency scaling
CPU frequency translation statistics - ON
CPU frequency translation statistics details - ON
Default CPUFreq governor - Userspace
'performance' governor - OFF
'powersave' governor - OFF
'ondemand' cpufreq policy governor - ON
'conservative' cpufreq governor - OFF
ACPI Processor P-States driver - ON

and finally select the proper chipset which is integrated in your laptop. If you do not know your hardware, use:
# lspci

Don't you know how to compile your own kernel? Follow these instructions ... http://www.howtoforge.com/forums/showthread.php?t=21