Template Width 940px,Screen resolution,Eff.Rotator

Sorry for my English (I'm Italian)
I bought your template, it's wonderful!
before starting to work it I would like to ask you if 780px corresponds to a screen resolution of 1024 x 768.

Thanks in advance.

Please describe more precisely why you are asking that.

Ok, I'm new in Joomla, sorry for my questions.
I would like to customize my website at width 940px having a correct horizontal visualization from 1024x768 screen resolution.
After changed the width I tried to move the effect rotator in the meddle of the page, but modifying the line 107 or 108
upper.
margin or padding
of the layout.css I have an horrible horizontal scrollbar...

Inspecting my webpage I changed this value:
#slider {
height: 413px;
margin: 0;
padding: 0;
position: relative;
width: 750px;

in :

#slider {
height: 413px;
margin: 0 85px;
padding: 0;
position: relative;
width: 750px;

It has worked fine, but i don't know which file I really have to modify... My inspectig software says it's 127.0.0.1/joomla (my website is installed on a local machine).
Please may you help me?
Thanks in advance.

[EDIT]:
PS: I found the file! It's the:
mod_hot_effects_rotator\tmpl\default.php Line 19

My problem is resolved.
Thanks