Congrats! I know you are going to enjoy it!
I use a King Canopy II (12x20) with bricks underneath it. Actually, mine is a less expensive version of it, but it does okay. I'd advise going with one that isn't prone to rusting, because I had to paint
mine after the first year. Also, don't skimp on the tarp. I bought a cheaper replacement that was actually made for it and it barely lasted one year. Save yourself the anguish and get a better one from the get go, that way the wind won't tear it up and it will last longer than one season. Mine is staked and guy-wired.
The only reason I went with that one instead of a hard-roofed model (Tuff Shed) is because I wasn't sure if it was going to work, so I didn't want the initial outlay (and I wasn't sure how my neighbors would react).
Having it covered has been a tremendous asset and I wouldn't do without it; however, mine still gets very dusty from blowing dirt. That doesn't really bother me, though. It washes off very easily and I like having it where I can work on it even in the bad weather.
This picture is a little dark, but you might be able to tell something from it. I really like having the 12 x 20 vs the 10 x 20. It allows me to keep the door open even if it's raining.