Site maintenance log in

I have tried to install my Zen cart onto my local server, but the xampp will not run my Zen cart.
To save the bother of messing about and also I need the shop to be viewed by other people while its in the build stage, but not the whole world.
Is there any way I can use the site down for maintenance page and have them log-in some how and then they can see the website.

Not really, but you can password-protect the site. Most hosting control panels have this option.

If those persons have static IP addresses, you can put their IP addresses in the maintenance IP list, and they'll be able to see the store as it would normally look even though it's in maintenance mode.
Admin->Configuration->Website Maintenance

And even if they don't have static addresses, if you give them an admin login, they can login and set themselves into the list as needed.

Thanks for the help, I will have a look and see what I can do, I have have built a few joomla websites and I can put the website off line and the users can log-in and see the website, before it go's live.
I was hoping to do the same with Zen cart

As I said, you can.

But, since this isn't a CMS which grants only certain users the ability to login to the front end, you just go about the process differently: as described above.