> I have a site running on my laptop <http://localhost>
> 
> This is a asp site running on IIS and the OS is
> windows xp.
> 
> I use winhttrack to browse this site and create the
> html output of the asp pages and store them for
> uploading on my static website later.
Good move. Why have dynamic pages when the output is mostly static. I have a
site I mirror: 12,000 index.php&ID=nnn which haven't changed from day one. Yet
httrack as to download each one of them since the timestamps have changed.

> The problem is that it downloads pages even if its
> content has not changed at all.
This is the problem with dynamic pages. The content changes each time, since
it is being created each time.

> Due to this, I am unable to determine which are
> pages of fresh content. And I am required to upload
> the entire set of about 2000 pages everyday.

I would suggest you write a script to compare todays pages with yesterdays.
Delete identical todays.  Upload remaining and then move todays to yesterdays.