Helping people with computers... one answer at a time.
Transferring files from one PC to another is an important part of moving to a new PC. Unfortunately, it's not the only part.
Recently I needed to purchase a new computer. I arranged for all of the data from my old computer to be placed on an external drive. When I open a file, it says that there is information there, but the programs will not run.
It is my assumption that the program, which was originally on a C drive is looking for information on a C drive instead of E where the information actually is.
Is there some way, other than purchasing the programs again that I would be able to make them work?
It really all depends on what you specifically mean by "open a file".
Placing all of your old hard drive's contents on an external drive is an excellent approach to moving from one computer to another.
But it's not the only thing you need to do.
If by "open a file" you mean you have a document - say a Microsoft Word document - which you locate on your external drive and double click on, then Microsoft Word or some compatible program that understand's Word documents must be installed on your new computer.
It's not enough that the Word program files might be on the old, now external drive. The program actually needs to be installed on your new computer - which typically means installed on the new computer's hard drive.
If you have the original installation media that you used to install Word onto your old computer you can just use that again to install it on this new computer.
Remember, Word here is just an example. I have no idea what kinds of data documents you might be working with. The concept applies though: your external drive contains your data files, and to open them you likely need a program installed on your new computer that knows how to work with whatever type of file it is you have.
And yes, if you don't have the original installation disks for the programs that were installed on your old computer, you do need to go out and get replacements. Remember, though, replacements don't have to be the exact same program - using Word as my example, that ".doc" file can also be read by the free Open Office Suite. It has its pros and cons, but it is free and might be a viable alternative. What alternatives work for you will depend once again on exactly what types of data files you're working with.
If by "open a file" you're attempting to run a program - perhaps you've found Word.exe on your old drive and are trying to run it from the old drive, then no - most of the time that will simply not work.
The rule of thumb is that if a program needed to be "setup" when it was first installed on your old computer then it will need to be set up again to work on the new. That means you'll need the original installation media in order to perform that setup.
That's why getting and keeping the original installation media is so important.
In short: data files work just fine from old hard drive, as long as you have some program installed on the new computer that knows how to open them. Program files typically do not work, and usually have to be reinstalled on the new computer.