Articles won't be too many but will increase over time. About 10 at first, but could go up to a 100 in the future?
Average article length would be around 700 words I presume.
It's a membership only section and personally I don't expect it to have more than 10-20 concurrent users accessing the same article at the same time. However, this figure could increase in the future as well.
Well that is why I am asking what your distribution is for the length of your articles. For the number of articles you are concerned about, this will not be an issue - I worked with several hundred thousand of articles in sql server and with more concurrent users than you with no problems. However, you need to be more diligent with your error checks on your tables that use them because they are more likely to have errors.
You will be ok - however, I would test the length of these articles and see if they are in fact text datatypes or long varchars. If you have a mix you can still use the text in row as well. Just make sure that if you use ntext/text datatypes to make sure that you have a frequent integrity check using dbcc checkdb.
Both checkdb and checktable check the integrity of the database/table. Since you are new to ms sql, I would recommend that you read the "books online" - this is an online reference utility for sql server.