Need Help in Uninstalling Files and Programs on Old to New

[klbhome]

I have a computer in which I bought at Best Buy several years ago and it came with software in whcih I was not provided any Cd's for. I am in the process of building another system currently and will want to uninstall some of the programs on the old computer and reinstall them on the new computer. Is there an application out there that will allow me to do this or any other solution to my problem other than buying the software a second time? I am running Windows XP Home Edition as my OS on the old and the new computers.