So I have a 7-8yr old win xp pc that is soon to be replaced and I was thinking of hooking it up to my router, installing freenas and using its 2 hdd's for general storage.
I have browsed some online articles but I have never tried anything like this before so my first question is, is this even possible or am I missing something?
If it is possible, my understanding is that I will need to use nas4free because it is an old xp pc, and I would install nas on a usb flash drive and set everything up before I steal the monitor for the new pc. Does this sound right, should I be looking at something like ubuntu instead?
Also are there any problems with both pc's and mac's using the storage (both kids have school supplied mac's during the school year)?
Yes, FreeNAS will definitely work for your purposes. The only thing you may want to consider is getting maybe 2-4GB of ram in the xp machine depending on how big those HDDs are going to be.
I setup a FreeNAS server about a year ago. I have had nothing but great success with it. I am still learning tons about it but since getting basic file sharing setup (which is very easy especially with all the tutorials setup) I now have a FTP server, Bit Torrent Client and mini dlna server all running inside of it, all available anywhere on the net. Long story short FreeNAS can do pretty much anything you want it to.