Is it OK to use my rewritten GNU program commercially?

[Inventor]

Hi,

I have released my sports prediction software under the GNU GPL, folks
are using it, and I plan to add the latest features for a 'final'
release.  The first version is a klugy hodgepodge of code with only a
command line interface, and now that I am learning the beginnings of
OOP and CGI, I am rewriting the program from scratch with a web front-
end.  The new code will have the same algorithm as the old code, but
is completely new in every other way.

My friend wants to possibly commercialize the new code someday,
setting up a web page and charging for either access or software or
datafeed.  Now, i'm fairly sure we could charge for datafeed since
that is not the program, just the data for the program, but could we
charge for access or software of the new program?  I would keep the
old program on the web for free in any case.

Is it OK to commercialize the new rewritten version, or have I given
that away for free as well?  Also, is it OK that we would have a free
command line version and a paid web version, or is that just plain
wrong to do?  I think it's OK because the new program is totally new,
but i thought I'd ask wiser folks to be sure.

Thanks in advance,
Inventor