You can get a computer's like this:
For linux (KDE Only): Open up SuperKaramba and get the system_monitor theme (it can be found at
http://www.kde-look.org/content/show.php?content=37963 . Open that up and you'll see the IP address in the "Networking" section of the widget. At this point I have no GNOME way. I don't really use GNOME outside of VMware.
For Windows (Windows XP): Open a DOS window and type "ipconfig" and you'll find your ip in there somewhere.
For Windows (2000 and lower): Open a run run box (Winkey+R) and type "winipcfg" to open the networking status box. You'll get more info than you ever needed about your network (and more) to keep you going.
Also,
http://www.dougknox.com/ has the winipcfg utilit for Windows XP if you want to download it.
To access shared files or printers:
In Linux(Again KDE Only, but GNOME may have this option): Go to My Computer>Samba Shares and choose the device you want to access.
In Windows(all):
Go to "My Network Places" (Differs in different Windows versions) Choose "Entire Network" and choose the device you want to access.
**NOTE** You can also access a computer by typing "\\IP-ADDRESS-OR-COMPUTER-NAME" in the Run box (Winkey+R)
To remotely access a Linux machine through SSH:
On Windows and Linux: Download and install Putty (
http://www.chiark.greenend.org.uk/~sgtatham/putty/)
Hope this helps.