Frustration Dept.

When backing up your computer on an external hard drive, does the whole program and data get backed up or just the data? My reason for asking is because I would like to replace my current desktop computer that has about 50GB listed on the hard drive. If I were to purchase a new computer could I also but an external hard drive, back up my old unit then transfer it to the new unit? Or, am I going about it in the wrong way?????
Your assistance will be gratefully appreciated!

Respectfully,
Richard Hyer, Jr.
jrhyer@comcast.net