Backup of Win98 PC’s on a Network-S/W

I’m wanting to backup my Win98 and a few Win95 PC’s that are on a real simply peer to peer network. They all have static IP addresses. I have also setup a VPN tunnel with one of our branches and would like to backup their PC’s as well. The thing is I want to backup certain file extensions and not the whole PC. Does anyone know of a software package that will backup PC’s on this type of network, by extensions, to a hard drive? I would back this off to tape during the day. The software doesn’t necessarily have to run on a Win98 PC because I would like to try Win2000.