I'm not smart, but I'll try anyhow. I'm on Leopard, and am able to connect with XP, Vista and other Macs no problem on my home network.
Problem is, networking in OSX works so well - I only do it once, and then forget, because I don't have trouble with it.
Unlike in XP, where I constantly had to rebuild network connections and workgroups to keep them up and running.
First - go to Spotlight and type "Sharing" - it should bring up your sharing Preference Pane for OSX. There should be a green "light" next to "File Sharing: On"
Otherwise, In that window Check off File Sharing to enable it. Set up the groups/users/PCs you want to share with. By default, "everyone" allows "Read Only" - you will need to evaluate how much you want to share - and how safe your network is, before you allow full access to some folders. (otherwise people can get in and start moving and deleting your files) Set what folders you want to share in the "Shared Folders" box by tapping the + key on the bottom. Be sure to Click the "Options" tab - and set what you need in there, too. I have share files and folders using AFP clicked.
Now, back in the main System Preferences window - Go into the "Network" preference pane - be sure your network is connected and active (indicated again, by the green "lights") If not, activate and make changes to be online with what your network is.
Back to System Preferences - Security
Click the "Firewall" tab and be sure File Sharing (AFP) or your other protocol is visible in there, and click "Set access for specific services and applications" be sure your file sharing isn't blocked off. Under Advanced - turn off "stealth mode" if you have it on - it may be giving the Vista computer problems locating your Mac. Obviously you can turn it back on when everything is happy.
Now - back to the Windows side - make sure you have file sharing enabled on your PC, and find out what Workgroup your PC is under (I renamed my PC workgroup to "Network", and what the PCs name and/or user account is. If networking and file sharing on the PC was not turned on, restart it after you have - otherwise it might not post the changes.
Now - on your OSX - click so you're in the Finder (so it says "Finder" on your menu bar up top) Under "Go" select "Network"
Inside that you "should" see connected computers on that Network. Double click on the computer / volume you want to Mount - It should ask you to Authenticate - and either leave the password field blank and hit enter - or put in your PC access credentials.
It should mount the drive. So that is what I did to get my network up and running - I don't completely remember it all, and I'm sure there is an easier setup than that. But it worked for me. I saved my login info for the PCs in my Keychain - and now I just double-click on the volume in my "Network" in finder when I need access to those PCs.
