Older computer

I have a hp pavilion a320n computer. I notice the more I reinstall XP from the same disk the more unstable it becomes with more errors poping up. I know the life span of a computer is about 3 to 5 years and I’ve had this one about 5. I don’t want to do any upgrading cause I know it’s better to replace it. is there a program, fix, or something I can do to get this this thing more stable like maybe trying a different OS. When your strapped for cash you do with what you have. Thanks for any suggestions. Bill.