windows xp and few problems

so ,i’m running xp pro with sp-1 installed on p 4 at 2.4 ghz ; few days ago i’ve uninstall NSW 2002 profesionall and after that i’ve got problems with office 2000, and windows…
now i can not do any install of any kind of antivirus or uninstall what left from the old one because the windows is freezing after uninstall command;and when i’m opening the office 2000 i can see the window for 1 second and then is closing suddenly…
i want to do an master boot record (MBR) but i don’t know how to do it right…
so i was thinking if any body could help me with some command concerning MBR …
thank you !
marius!