wine users - Dec 2010 - Separate isolated instances of programs

I was wanting to know if Wine is able to make private or semi-isolated instances
of programs at a time.  For example, separate windows of the Steam gaming
platform if it's possible.

I'm new to using Wine, but have used Linux, so I have some knowledge of
technical stuff.

I think that if you use separate Wine prefixes you can isolate programs.
To do this, just type this on the terminal:

WINEPREFIX="<name of some clean folder for the prefix>" wine
<name of the program>