okay, printer is hooked up to the main computer.
i went control panel > printers > "Share this printer"
then on the computer i'm currently on, i tried to find the printer under "add a printer connected to another computer", but i can't find it anywhere in the network list and such.
On that computer, right-click on Start, choose explore. click on my network places, click on entire network, click on Microsoft Windows Network. You should see one (1) network - whatever you have named your network. click on that network and you should see all the devices connected to that network, including the "main computer" attached to the printer. if you click on that computer, you should see the shared printer.
if you don't see both the main computer and the computer you are on, perhaps the two computers have named the network differently? to check this, follow this same procedure on the main computer and see if the network name is the same on both computers - it must be, to share resources and you said you are sharing internet connection of main computer? so this shouldn't be a problem.
if you do see both the main computer and the one you are on, then it may be a browsing issue in the printer install program. to get around this try putting in a specific address, such as: \\<the exact name of the main computer (as shown in explorer)>\<the exact name of the printer (as shown in explorer)>
file and printer sharing must be in the network properties of both computers. to check this, right-click on my network, choose Properties, right-click on on the network and confirm that Microsoft file and printer sharing is enabled. if it isn't there, click on Install button, highlight Service and click on Add, highlight Microsoft file and printer sharing and OK your way back out (XP CD may be required).
there are plenty of other possibilities, but 1 of these 3 seems most likely, IMHO. at least a place to start