It's a perfectly legitimate cast on. There are many ways to cast on. You'll discover some advantages and disadvantages to each way. Your method (sometimes called backwards loop cast on) is easy to do
, but can be tough to knit off of (the little loops are tight and hard to get your needle into). Also, it can look a little sloppier than other methods of casting on.
The long-tail cast-on, once you learn to do it, is almost as fast, and it sets you up for a much easier time when knitting your first row.
Amy has videos for several different cast-ons (casts-on?) at this page: http://www.knittinghelp.com/knitting...ques/index.php
. Note that your method, called single cast-on, is there.
Give all of them a try -- it's worth knowing more than one way!