Internet working really slow?

[+Stitches+]

My internet takes a really long time to load. I have Vista. I had the same problem when I used McAfee, then switched to CA, which is working great, but the internet got slower since I reformatted my pc. When I re-installed CA after formatting, it asked me to choose the firewall options, which I think I chose only one b4, could this have made a difference? How would I change it? I use IE7, Comcast high-speed, if this makes any difference.
i went into my firewall options and found how to change it, but still slow