Softbox or another umbrella for 580EXII?

I currently only have a shoot through umbrella for my light but would like a softbox for it.

Seems like most need a speed ring, but I'm not sure where to start with figuring out what ring I would need and what box will go with it.

Or should I get a reflective umbrella instead....or both?

Most speedlite softboxes come with the ring. For example Qbox24 comes with one as does Lastolite.

Umbrellas are cheap but they are difficult to control your light and they tend to fly away pretty easily when shooting outside.

If you only have a shoot through, you may want to consider a brolly or a SB. The 46" Softlighter is pretty cheap and gives you more spill control.

http://www.google.com …AK7mNS0Dg&ved=0​CDEQ8wIwAw