vista help.

so i used to play with xp with fps 80+
my comp is however broken atm so i am using mom's pc yes xD
it has VISTA i have never used vista and i get fps 10-25 almoust same system specs than my comp but why fps so bad?
processor: 1.9Ghz
RAM: 4gb ddr2
video card: ati radeon x1250

almoust same than my xp machine but soo low fps
css run around 40+ fps
tf2 around 30+ fps

so give me VISTA tips for better fps plox?

help me i am forced to play with kriss,skill light to get 1kd
i want to snipe again

and why my sprays ingame look like this