Upgrade questions

I have a Compaq and would like to upgrade to a Dell, which is sitting at a reapir shop - someone traded it in for a laptop. The system is fine; no problems with it. I would like to basically take my C drive out of the Compaq and put it in the Dell - so it would be exactly the same, just better processor, more RAM, etc... How exactly would you do this to arrive at the intended result? What considerations, etc...
Thanks.

What os are you running?

Example :- if you have XP the activation takes place and it records the hardware you are running it on. As you are intending swapping computers, obviously the hardware would be completely different, and you would have to contact Microsoft to re-activate XP on the new hardware

Oh yes, sorry - it's XP home.

yes i have formated a lap top c:format c: now i am trying to install windows 98 or 2000 on it but it trys to boot from the cd but it just spins up never trys to boot from floppy i have reset the boot seguances but still no boot up please he;p

Is the CD you're using an original? It sounds as if it may not be a bootable CD. Have you tried booting another computer using the cd, to be sure that's not the problem?