I have been taking classes online for about 1 1/2 years now at American Public University, and there are a few things you should definitely purchase and/or have on hand to help you be successful.
1) Access to a notebook and one additional computer, both with Microsoft Office 2007 or newer.
I typically use my notebook, but when that went out, I used my desktop. Now my desktop needs repair, but I have my notebook. Online classes don't stop for computer problems. Also, don't try to get by without Microsoft Office. Some classes will have requirements that pretty much force you to use Office. Having at least one of your computers be a notebook gives you a tremendous amount of flexibility in studying and completing assignments.
2) MLA/APA/Chicago templates for Microsoft Word
I got mine from www.referencepointsoftware.net . These will be an invaluable life saver.
3) A current style guide.
You are likely to have to purchase one as part of an English class, but if not, get one. This will tell you all the rules about how your papers should be formatted. You will want to refer to it anytime you are not sure what to do or what things should look like. I use the one by Diana Hacker.
4) Subscription to Easybib.com
This tool will make it snap to generate reference lists for your papers and other assignments in whichever format you need. Most of the time, entering a web address or ISBN is sufficient to generate a properly formatted reference. It will tell you what information is needed. Also, it has a feature that will generate proper citations. Invaluable!
5) Subscription to the Encyclopedia Britannica online
This one is a little pricey at $69/yr, but it is a real help given the fact that most professors dislike or outright ban Wikipedia references. Use Encyclopedia Britannica online instead and you can present it as a reputable source. Very easy to lookup almost anything, and each article provides relevant outside web sites to also check out.
6) A printer
Before submitting that paper online, print it out. You really need to make sure it looks good printed, and there is nothing to compare with reading your printed out assignment for finding mistakes and errors.
You will likely be using multiple computers for your studying. Keep your college files and assignments automatically synched across all your devices with dropbox.com. Another tool you can't go without.
8) Have more than one browser loaded on your computer
It is often easier or advisable to have your virtual classroom loaded in one browser while using another for research. If a rogue website takes down your browser you don't want to lose work if you are typing directly into the classroom.
9) PDFSam ( www.pdfsam.org )
Download your PDF-based e-textbook chapters and combine them with PDFSam. You will have a whole-book PDF that is great for searching. Go a step further and do a select-all in your whole book PDF and paste into Notepad, then save as a text file for super-fast searching of the entire textbook.
10) The local library
Explore your local library's inter-library lending programs. Often they will have agreements with local universities that make their entire collections available for you to borrow. Never underestimate the advantage of real-life books in online learning. Even if your online course doesn't require a lot of research, grabbing related books from the library puts additional information and perspectives at your fingertips. Additionally, most libraries have free wifi, making it a great backup connection in case your internet goes out. Just take your notebook to the library!