Is the Boss giving the PC to you or just loaning it? If it's a loaner I wouldn't add your programs to it just in case he wants it back!
If he is giving it to you, that's another matter.
Yes, you could remove "YOUR" harddrive and add it to the boss' PC. Make sure the Boss' HDD is jumpered as Master and yours as slave. Now you can move or copy your files to the boss' HDD.
Certain programs (MS Money and Outlook) will need to be reinstalled to the boss' HDD. I'm sure other members will want to comment too.