Hi, Im new to samba myself but I will be wanting to so the same and network a couple of machines.
Do a search on networks here on the samba forum and have a read through them.
What I have found is that you will need to install sql express on the server and then point the data file to the server on the other machines in your setup.
sql compact is fine for stand alone but no good for sharing over a network.
This post should help a little
http://forum2.sambapos.org/index.php/topic,74.msg575.html#msg575I will be having a play around with it later this week hopefully so I will check back and see if you have had any joy.
Personally I will be sticking to the same os on all machines as I know that networking between say xp and 7 never runs smoothly. Homegroup machines work fine and normally together as do the older xp network sharing.
I dont know how much experience you have with networking but the best advice I ever found out was to make sure all machines are communicating perfectly with each other before you even attempt to get the software to do it. It will save you a lot of time in the long run. Also modern routers seem to have a problem with name serving so I would say stick to networking basics and assign static ips to all your machines or privately pooled ips from your router and use the ip not dns in your settings.
I put a request on the forum for a hardware section that all questions and help for a specific type of hardware could be put under. This is a good example of when it can be used. All the info is on the forum if you search but it would be nice to have it in one place,
Hope this helps you a little to get you started.
Cheers
Matt
