How do I clone my new hard drive and make it my boot drive?

I have a compaq presario and am using Windows XP. I recently purchased a 1TB hard drive to add or replace my exsisting hard drive. Right now i have it in there just as added storage space but really need to have it running the show seeing how it's almost 8 times the size of my current hard drive. I have put a few programs and documents over on the new drive (just stored there) and want to know if I clone my C drive onto my new HD will I lose the stuff that's on the new HD already? Or will it keep those things in addition to bringing all my other stuff over? Also, is it a simple process like the instruction book that came with my hard drive says or is it way too complicated for a non computer techie to handle? You're suggestions are greatly appreciated!