Moving the main network site to a sub-domain

Quick bit of background info:
I had a site set to tell people about things going on locally.
After a while I decided to expand and have multiple sites so that I could cover other areas.
To do this I converted it to a multisite network.
I now have the main domain (say http://www.mysite.com) which has all the posts and data set up for the original area and subdomains (say area2.mysite.com and area3.mysite.com) with posts and data on them for their areas.

PhpMyAdmin shows that I have one main database with tables such as wp_site and wp_posts (which the original areas data) and others such as wp_2_posts and wp_3_posts (which contain area 2 and 3’s data).

Now, I’d really prefer to have http://www.mysite.com to be a main network site that has information about the network of sites and links to each area.

This means I’d really like to be able to move the contents of the main domain (www.mysite.com) to a new subdomain (area3.mysite.com).

How do I achieve this?
Has anyone managed it?

My initial thoughts were to use the wordpress export on the main site and then switch to a new subdomain and use the import. This didn’t seem to work offline however (may have timed out as my local wamp server is running really slow).

Any idea if this should work and how it should be done? Any other ideas howto do this? Please bear in mind that this is my first site and I am not an expert at this stuff.

Cheers.