I believe your computer may have been an older one since you did not even have service pack one as yet. I have windows vista and finished an install of service pack 3 awhile back.
And memory is very important as well....
Remember this in a computer upgrade and/or install
Put in as much memory as you can afford, fill it up completely if possible.
Have as high end cpu as your motherboard will take.
The three main things in computers is..
CPU
MEMORY,MEMORY,MEMORY