Whats more benficial..

[Rob.Richards]

I currently (as some of you may know!) have a a 1 light set up with softbox and now a stand too! Anyhow, am I better investing in an additional flash or a background and support...

To clarify this is for shooting portraits with up to 4 people...

 

[getnoticed]

Another flash for starters (and another softbox or umbrella + stand)

If you shoot outside you may not need a background
Inside, you could use one flash to blow a wall white, or bring your subjects closer to you and use both flashes on them instead, with a black background created in camera

 

[Garry Edwards]

The background is the last thing that I would buy, given budget limitations.
I always believe that knowledge and imagination is way more important than equipment, and that naturally-occuring backgrounds are often much better than 'studio' backgrounds.

 

[Rob.Richards]

Hmm thats great and the way I was thinking too! Cheers for the input!