Are you on dialup? If so, about your slow webmail, I copied this concise and accurate explanation from The University of Chicago's FAQ, which should do it.
"As a web-based program, it has a lot of overhead that slows down the process of checking mail. It is not intended to be used as a primary mail client. By reducing the size of your inbox and reducing the number of filters you are using, however, you can significantly speed up your experience."
Forget the part about the filters. But reducing a big inbox should make a difference. And if your computer has enough RAM for an e-mail client, go for it! Like Mozilla Thunderbird at
www.mozilla.org.
About your downloads, when you are downloading files from the internet, it can slow your internet. Think of it like this. The pipes that carry the traffic are being filled by the download, so your regular surfing speed diminishes, to a tiny piece of the pipe. When your downloads are over, you get the full pipe back for surfing. For people with broadband, think of a much bigger pipe, making it more difficult for downloads to interrupt usual surfing speed.
Another thing to try (there is much to try and this is by no means a comprehensive list) is use a program like Crap Cleaner. Yes, Crap Cleaner, if you have never heard of it. Besides the awesome name, it is an awesome program that cleans temporary internet files, cookies, etc.
And oh yeah, if possible, stop using IE. At
www.mozilla.org, get Mozilla Firefox. It's safer, has better features, and I think faster page rendering. It's free, and most people switch for security. Wait til you try tabbed browsing, if you have not, it is an innovative idea. Like the Gillette Mach 3. Or Tivo. Some ideas are great. Tabbed Browsing is great. Hope this post helps get ya in the right direction.