You can set up your laptop to do it when it's on with something like SyncToy (a Microsoft download), and at a push I think some drives might support it natively, I haven't investigated. Alternatively, you could have a small PC running windows Home Server to do it, but that might be one box too many for you.
And no, I can't convince you that a squeezebox/NAS combo isn't a faff - I'd be alright because my Mac is on all the time, and so could act as the server, with the files on the network, but installing Squeezeserver on a NAS drive, unless it's pre-installed, looks like my idea of hell.