WInXP & ATI Radeon 7000 series headache

Please can someone help me… I just installed WinXP on a computer… I am using 128MB RAM…. and this ATI Radeon 7000 series AGP video adapter… Whenever I try to install a program (eg Corel office siute, Imaging software, Norton Anti virus), thesystem runs for a while and reboots mid stream installation… I have updated the AGP drivers for the motherboard, the display drivers and control drivers for ATI but the problem recurrs… Please I need advice as to how to solve this problem…. Please assist..