Access network shares remotely ?

I have 3 new systems on the way for them, but they have some questions about remote access and other things. I am familiar with networking, but not to the same extent as many people here, so I thought it best to ask first.

Their current network is setup like this:
Server: (Running Server 2003) all files are located and worked on here, shares are all password protected. Internet access.

5 Computers: (Running XP Pro) server's shares are mapped to each computer, all programs needed are installed and run from each computer. All have internet access

my question is that is it possible to configure the server to allow remote access from their houses (all running xp pro) to just the networked files? I'm currently playing around with realVNC on my computers at home, but its not exactly what I am looking for. I was thinking either, remote desktop to their own desktops at work, or virtual machines on the server which they could RD into. I am fairly new to the remote management world, so any help is greatly appreciated!

Try to use VPN. its the most Safest and most secure. try hamachi (zero-configuration virtual private network (VPN) application)

Thank you bigfish, i would like to use it as soon as possible.

Remote desktop works the best. Takes for frikin ever to upload and download data of any size. Way faster to have them remote desktop in and work as if they were sitting there.