I am currently running PCLinuxOS on my Dell Dimension 4500. I'm having problems with PCLinux and would like to install Ubuntu over it. If I do that, will my files be retained? Is there anything I need to do to ensure that they are not lost?
You shouldn't have any loss of data if you install Ubuntu on your hard disk as a dual boot system. But since you want to install over, I would highly recommend that you backup all that you need before installing Ubuntu, because you will lose your data, since the installation will erase your partition.
If you are just concerned about your files, just do a backup by copying the files you want to keep, such as your entire home directory, to an external hard drive or usb. To answer your question on whether you files will be retained if you just install over PCLinuxOS, the answer is no they will not.
Hope that helps!
Installing Ubuntu over PCLinux will cause the PCLinux partition to be formatted (wiped) - any data on it will be lost. Unless your hard disk has multiple partitions - or your computer has multiple hard disks - to which you can move your files, you will need to back them up onto a memory stick or external hard drive before you install Ubuntu.
The following web links may be of use: