If I purchase a Hard Drive enclosure for an old hard drive I understand that I will be able to access and add files for storage but will I also be able to launch previously installed programs?
Upon adding an older hard drive to a new build with either a usb adapter or with a 5 1/4" drive bay adapter like the one here,
you may or may not have ready access to the drive if the one or more partitions on it are NTFS or Linux while you are let's say running Windows 98. Or you may have to use some recovery method like a live for cd Linux distro like Knoppix to recover files from it. As far as running any programs installed to it that would depend on whether they were older dos games or much more recent versions for ME, 2000, XP.
Your operating system if originally installed onto that drive would have to be loaded in order to run programs previously installed to that drive since all entries into the system registry would have been left on the original host drive if any custom installations were made. Those would have to reinstalled in order to see them run if they are compatible to the current OS you are running now.
So if I purchased a 3.5" USB 2.0 Hard Drive Enclosure I could only access and add files and not access programs programs installed due to the operating system? I am asking because I have an old desktop running Win95 that I am wanting to connect to a laptop running WinXP and access programs such as Adobe and MS Office programs. I did not want to have to install them on the laptop if I did not need too in order for them to work.
For one thing any desktop applications that old would most likely not even run under XP. You would have to install the updated versions. Adobe Reader will automatically update itself when installed onto an XP system even a laptop. You should be able to retrieve any remaining files since XP can easily access Fat16 partitions. So you haven't lost any files but programs only.
Once you have copied anything important off of the old 95 drive you can reformat it to NTFS which is far better to start with. For installing programs to it by custom selecting the creation of folders there you may run into problems through a usb type adapter however. Adobe itself only takes up a small amount of space. For the old 95 MS apps that is like trying to run some 9X-ME/2K/XP softwares on the Vista installation on one drive here. "Mission Impossible"!