Re: best pop up BLOCKER !!!
Firefox, itself does a pretty decent job of blocking pop-ups. You might need to set the options correctly.
If you have a toolbar (Yahoo!, Google, and MSN, etc), it will take longer to open FireFox, IE, or any other browser for that matter.
If you are using a slow dial-up connection, MSN appears to hang for a while and system slows down to a crawl. I have noticed that as well, even with 1GB RAM and an AMD Athlon XP3000 processor.