I am doing through this right now for DH -- and I am not a novice having worked in the software industry for about 20 years.
Unfortunately, just copying everything from one computer to another is does not usually work. You can copy all of the files and data but you need to reinstall your programs using the original disks -- copying them does not work unless the ctwo computers are identical.
Nannamoms idea about contacting Dell to see if they have a refurbished computer like yours would be a good way to go --if you can get a good used laptop with XP that would be the best way to go, that way you can be sure the programs you have will run on the new computer.
I have some programs that ran on XP that work just fine on Windows 7, but I have had to replace other programs that were designed for Vista with newer versions.
PM me if you have questions and I will give you more information.