What you want to use is the Offline Files feature that came in with Windows 2000. It really is superb. I don't have XP, but I assume that the features exist in XP although they may be found in different places.
I assume that you've already got the 2 PC networking OK.
1)Create a folder on your PC (called e.g. Daughter's Files or whatever) where you want your daughters files to reside.
2) Create a network share for Daughter's Files.
3) From your daughter's PC, navigate to 'Daughter's Files' on your PC via Network Neighbourhood->Microsoft Windows Network (don't connect to it with a network drive).
4) Copy all of your daughter's files across the network into 'Daughter's Files' on your machine. (Just copy, don't move them at this stage until you're confident it's all working OK, then you can delete them off your daughter's PC if you want).
5) On your daughter's PC, go to Control Panel -> Folder options -> Offline Files tab. Check 'Enable Offline files' and 'Synchronize all offline files before logging off' if desired.
(Note this is for Win2K, XP may be slightly different).
6) On yout daughter's PC, in Windows Explorer, right-click 'Daughter's Files' on your PC, then select 'Make Available Offline'. This will then copy the files and folders from 'Daughter's Files' on your PC to a hidden cache on your daughters PC.
7) To synchronize manually, run Programs -> Accessories -> Synchronize.
Whenever synchronize runs, if a file has changed on one of the machines, it will copy it to the other machine, if they have both changed, then it will tell you and give you various options.
The above behaviour is configurable, as is where the cache is stored and it's size.
When your daughter can't connect to your machine (e.g. your machine is switched off or one of them is no longer on the network), she still accesses the files through Network Neighbourhood and your PC appears as though it still connected to your daugter's via the network.
This functionality is completely achievd on the client end, i.e. your daughter's PC in this case. Your PC is merely a file server.
I use this technique at home. I have an old Dell 180Mhz Pentium PC running NT4.0 which I use as my file server. My wife and I both have notebooks which synchronize with the NT4.0 machine. I synchronize with Gary's Folders and Shared Folders and my wife synchronizes with Helen's Folders and Shared Folders. (Note NT4.0 doesn't have any Offline files capability, it is merely acting as a file server).
It works brilliantly - the best thing about Windows 2000!
Anymore questions, please ask.
Hope that helps,
Gary Cooper