I have an older dell computer, 450mhz, 512ram w/13gb. I would like to replace the 13gb with a 300gb. What is the best way to move all of my files & operating system (xp pro) to the new hard drive. I know if you move some files that the licenses would have issues. This computer originally had win 98 and I upgraded to xp pro.

   Some harddrives come with software which will transfer the files from one drive to the other.  I think that at least one of the harddrive manufacturers has that software on their website.
   If you don't go that route and you still want to copy the files over, you should get software that transfers an image and not the individual files over.  Drive Image XML is a freeware program that can do that.
   With either one of the above options, you need to make sure that the new drive ends up with the drive letter of the old drive or you will end up with all kinds of problems.
   Another possibility is to add the new drive as an extra drive and still use your old drive to run the operating system and the old programs.

lots of ways.  if the hard drive is a good one then why not keep it and use it as a backup or for other things.  you can either make it secondary inside or purchase a very inexpensive external case.  by installing it in an external case, you can plug it into a USB port and use it as an external hard drive.  once installed, you can just copy and past your existing files to the new hard drive or just leave them there and access them as needed.