I was just wondering if there is an 'easy' way to update a skin. I have made very minor changes in the menu and footer. I created the template in Artisteer and I have zipped it and exported it.  If I go to the extensions wizard, will I have to reinstalll everything and will it write over the old files? I also have content in my zipped file. I am finding it very sloooowww.

Any suggestions or tips on this process would be helpful.

Updating a skin really depends on where you are working on the skin.  Since you said you were working in Artisteer, then you should be able to just have it export the packaged skin directly.  It has been a few years since I used it but I am pretty sure that is still an option.

Once you have the packaged skin, it is just a matter of re-installing the skin.  It will overwrite all of the old skin files and assuming you didn't change any of the layout names everything should just work.

As for content - you really should avoid including any content in your skin.  If you find yourself including text or anything beyond background imagery in your skin they you might want to rethink your approach.  Skins are intended to only provide the design elements of the site.  All content should be managed through the use of various modules.  If you keep this separation you will have a much easier time in site maintenance and upgrades.