responsive theme for opencart 1.5.4 or upgrade opencart?

I am new here and I need basic information about opencart and themes.

I have opencart 1.5.4 and OC2 theme.

I would like to use a responsive theme, but somebody told me is not possible in opencart 1.5.4.

Is it true? should I updgrade opencart? is neccesary?
In this case, is it free to upgrade opencart?

Thanks in advance

you should probably upgrade to latest v.1.5.6.5, and possibly by help of someone like this, PEKU is
offering the last 1.5.6.5_rc OC Version packed into a full OC-2 default looking responsive Theme.

And PEKU would also know, how to upgrade your v.1.5.4 DB, to make it work in v.1.5.6.5.
http://www.opencart.com/index.php?route ... n_id=23641
http://www.opencart.com/index.php?route ... rname=peku
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The advantage, compared with a full V.2, would be, that you won't have to handle an entirely new
ADMIN Console, and waste a lot of time, just to find out, what has been moved where, and how it works.
In addition, most of your existing Extensions would probably easy be able, to match/update to v.1.5.6.5 as well.
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But the most important Reason, you would not have to worry about the next Update, to stay ahead,
there won't be any, besides of possibly a few small fixes, it already works well, as it comes. It's a proven fact!

Just joking !
Ernie

PS: There are others, responsive Themes as well as good DEV's.
But I mentioned PEKU only, because he has 'em BOTH, the Knowledge and the Theme !
Just to mention this, not beeing related to anyone around OC.