Reformating a hard drve, problems

OK
I have a friends computer. It's an Emachine. I am attempting to reformat his C drive. I have tried going to the command promt and formatting, but I get the "cannot lock the drive. The volume is still in use".

So, I installed his recovery disk and let it boot up with that.
It says-
1. Restore windows XP
2. Boot to command promt from CD
Pleases select 1 or 2

It won't let me select anything. It pauses for a bit, then brings up an "A" prompt, which still won't let me type anything.

So..........

I tried using my XP disk to boot from. It say's press any key to boot from the CD. I press keys, but it keeps wanting to reboot in the original format and I get no disk options. It just goes to the original windows desktop.
I tried going at it from within by exploring the disk and running from there, but it says it's an older version and doesn't give me the option of putting the older version on.

What to do?????

Thanks

OK got the problem.
I was using a USB keyboard that wasn't letting me do anything.

Thanks

How would possibly expect to be able to format a hard drive while you are inside its operating system and using it?...Logically speaking, to run command promt, you need a service or process so deleting your OS would not allow your CMD to run at all and once you delete the OS, how would you format it back into the correct filesystem??? You would obviously need some other means to connect to the hard drive like a CD or something. ITs okay though, I'll give computer noobs a break Anyway good luck.