lazer1978,
So it looks like you want to eliminate your friend's PC and install both his hard drive and your hard drives into your PC - making his larger hard drive the primary OS drive on your PC and his drive a seconday data drive - correct?
There are two approaches:
1) Clone and Resize your drive's primary partition to your friend's larger drive. This will create a replica of your hard drives (Windows, data, programs and all) onto his larger drive with a larger partition. You'd then install your drive as a secondary, slave drive - reformat is as Drive D (or E depending on if you have a CD/DVD ROM drive). This solution would be the cleanest in that you won't have to reinstall Windows and all of your programs.
2) Put BOTH drives in your system - making your friend's larger drive as "Primary" and your old drive as "Secondary" or slave. Perform a fresh install of Windows from scratch onto your friend's larger drive - reinstall all programs and data.
In option #1, you'll need a cloning program such as Xxclone:
http://www.xxclone.com/
to Clone your old smaller drive to your friend's larger drive. Both drives must be connected to the same PC (doesn't matter which one).
In this scenario, you'll be wiping out your friends OS, Programs and data - in which case you'll first want to backup any of his data, favorites, documents, music, pictures, videoes, etc. to either removeable media (USB flash drive, external hard drive, CD/DVD recordable discs, the Internet, etc.) BEFORE you clone your drive over his.
In scenario #2, you'll need to backup the data, docs, music, favorites, etc. on your friend's hard drive BEFORE you install a fresh copy of Windows on top of it. If you format YOUR old hard drive as a secondary data drive, you'll also need to backup any data on THAT drive as well.
If you have any specific questions about either method, let me know.
- John