|"i was getting this problem even before installing ubuntu"|
You won't get a GRUB error on a "pure" XP system. GRUB is generally loaded with Linux, unless you loaded a different distro prior to Ubuntu? Or some sort of boot manager software?
"i am getting a lot of blue screens on my startup"
Could be a sign of bad RAM or incorrect memory settings. Are there STOP: error codes on the blue screens? Post the error message....