grub option pls explain
 

kernel /boot/vmlinuz root=/dev/hda2 ro ramdisk_size=100000 lang=us apm=power-off nomce vga=791
above is a line from my grub config file.
can you explain me the meanings of the following parameters and their options:
"nomce"
"vga"

These are just kernel params, not grub ones.
vga: you use vga graphical console, for example you can enjoy tux picture on kernel load, right?
mce: IA32 Machine Check Exception. It is a rather technical thing about stability, like querying temperature.

Look linux/Documentation/kernel-parameters.txt

Grub usually passes some kernel parameters in the kernel line. These are necessary to boot the machine. Not all of them are always necessary, but if it works leave it. You'll learn what that stuff means. It really wouldn't be meaningful to give a full explanation because the explanation is difficult to understand, also.