Win XP users can't install Norton v22.x products if they have an older CPU that does not support the SSE2 (link is external) instruction set
FWIW, If you don't know how to find out whether or not you have the SSE2 instruction set which is one of sequence of sets that are around, I found the easy way to check is to download and run the free Speccy tool -- click on the Piriform link in the left column which is the free version and not the free trial of the paid for version -- and after it has scanned your system check the entries under CPU where you should find your equivalent to this for my CPU on a Windows 7 system I built when 7 came out.
Before this one I had built an XP one and had to check that for a much older CPU but did find it had SSE2
Speccy is so useful and easy to use that I find it invaluable and it covers an amazing range of data including internal temperatures etc .... as you can see one advantage is that you can copy/paste any of the information you can see.
Do you have the latest Win XP SP3 service pack, and do you see any warnings or errors messages during the installation process? Is this the first time you have tried to install a Norton product on this computer, and has another antivirus program (e.g., McAfee, Kaspersky, AVG, etc.) ever been installed on this computer?