After extracting a tar...is tar useless?
 

If i extract a tar file using tar command,
a new directory is created with the appropriate files.

Is the original .tar file useless at that point?

yes, unless you particularly want to keep it - I wait until I have many tarballs with libraries etc on then burn them to CD so I don't need to redownload them if I ever want to reinstall my system.

Short answer is yes.

How about the directory and it's files?
 

OK, I understand that the tar file is basically bakup at that point, but what about the directory that is created by the tar command.

If I successfully install the program, is that directory and its files also backup now?

If you've done 'make install' then yes.

Thanks again for your help Komakino.

Learning a new OS can be a humbling experience.

Tell me about it...I'm still learning!

Yeah, only reason why you'd want to keep the install directory around is if you wanted to reconfigure the app you just installed. I did this recently, with vim, had to work the ./configure about 3 times before I got it just the way I wanted. I regularly go through my install directory and do an ls -l | grep drw to see what directories I have just sitting around pimpin' electrons.