Does anyone know how to make Windows XP Pro and Win 7 Pro see each other and share files?
AFAIK, you just set up regular file sharing on a network. This usually means you right click on the folder you want to share and then click on “Properties” and “Sharing.”
XP has workgroups, and Seven has “Homeboys” or “Homegroups” or something. 
I always have to install the “Link Layer Topology Discovery Responder” on my XP machines to get them to talk to Vista and 7:
MS says with service pack 3 I don’t need it.
No joy so far, darn it.
Setting up the network options in Win7 is obscure and difficult. It should all be together under “Network” but it’s all over the place.
First, shut HomeGroups off. This feature only works for two Win7 computers talking to each other.
Next, you can define your Workgroup (which by default is MSHOME in WinXP) in the Control Panel under “System/Computer Name”.
You must run the network wizard in XP after you have done this. Reboot both computers and they should be able to see one another. Since Win7 demands passwords for user accounts, you will have to log in to access Win7 shared folders from XP. XP, lacking such protections, is wide open to 7.
For the sake of ease I suggest dragging and dropping stuff into the Shared folders as that is the default of where your machines will look for files on the other computer.
Thanks, DWMarch!
Obviously whether this advice is good depends on your work practices, but in my case, that would not be a good idea. I would have to drag 10TB of files into a special folder when all I want is for multiple machines to share any and all resources when called upon to do so.
Well if you are in an environment with 10TB of mission critical files needed by multiple users you are probably running a bit more complex environment than 2 desktop boxes.
Assuming you do not want to implement a domain a NAS Array might be an excellent option and would allow all manner of redundancy and availability.
Yes, it would, but it would also increase the cost, and cost is a high priority. It is under consideration. (System is basically 3 desktop boxes, inactive hard drives in offline storage, remote high-speed connections and the occasional passing laptop)
Well I personally assumed the “unless you’re moving 10TB of files at a time” was obvious but your data transfer needs may vary. 
I have little experience needing to access or move that much data at a time but I think you’d need something like a Windows Home Server to access any and all resources at any time. See Paul Thurrott’s excellent resources here:
My point is you don’t need to move any data just to access it from other places. That’s what a network is for. And no, you don’t need a Windows Server to create or manage a network.
The suggestion of putting data in the Shared Folders works only for small amounts of data, where you cannot tolerate access by others to larger resource areas and don’t want to flag entire folders as shared.
It’s a privacy thing. I don’t want everyone in my network digging around in my good porn. They can find that stuff on their own like I did!
Also, I have found that adding the network to the equation makes file performance much slower. Say for example you are streaming a video. Much faster to move it to the destination computer rather than trying to play it from the source.
I suggested the Home Server for your scenario of the three desktops, unattached hard drives, remote connections and random laptops. WHS would seem to tie these all together nicely. But feel free to fight my ignorance on this- there’s a way to tie them all together with plain old networking? It sounds to me like it would be quite a battle but I’ve never tried it myself so I’d love to know how it actually works.
It’s not without a hassle factor, but if you set the root of all drives to be shared, ignoring the dire warnings that predict an early Armageddon, it works. Printers can be shared similarly. Other devices should be sharable, although I haven’t tried much in that category.
You might not want to do this if you have a wireless access system, as you are also sharing with anyone who connects. In that case, passwords or some restrictions might be wise (don’t allow others to modify your files, for example).
In my case, since I am the only one sharing anything with myself, I don’t mind if I paw thru my own porn collection.
And it is infinitely easier if all machines use the same operating system version.
Forgot to mention: you will need the computers tied together either with a router or peer to peer, or both.