I agree that a sweater takes a lot of work and good yarn feels, washes, and knits better (usually.....) But I can also understand that you want to start w/o making a big investment to see if you like it. Worst comes to worst, it goes to the Salvation Army!
I think the important thing first is to see what kind of needles the yarn recommends, and how many stitches to the inch and rows to the inch they say you will get. Test it yourself, b/c it doesn't always play to the script. That's called a "swatch" and you can see how your own personal knitting ends up. That's called your "gauge". So you now know, in whatever stitch you chose to make your stitches in (that's important too, b/c when you try a different type of stitch, you may end up with a different gauge) that you'll be looking for a sweater with that gauge. If you're a die-hard, you may even want to wash and block your swatch to see if it changes in size. They say that testing gauge is the most important step before starting a project. You can use bigger needles to get a bigger gauge or smaller needles to get a finer gauge, but usually yarn is what it is and you can't make it do what it ain't supposed to.
Then there are many wonderful compendiums (compendia?) of free patterns on the net. You might want to start off with http://www.knittingpatterncentral.com/list_new_patts.php. Poke around to find something that a) you like b) is close to your gauge and c) is relatively uncomplicated, like a sleeveless shell.
Then go to it, and come back here and ask questions! Good luck!