How much free disk space is there on your hard drive? Things slow up drastically when it gets below about 15%.
Check for viruses! I'd also be inclined to dump the "paid for" AV and use AVG - it's free, it's extremely reliable, and it doesn't clog up the machine like Norton and McAfee do.
You can't "remove" IE from your machine without a major effort, but try switching to Firefox - it has many advantages. You may like it enough to switch your e-mail to its brother Thunderbird.