PAHU's method is good for getting the mac to sniff out the shared windows printer on the same workgroup, however, sometimes (like in my case) my macbook refused to place nicely with my windows shared printer for a while, so I had to resort to using the printer via IP method.
I ended up doing a version of the fix listed at:
http://discussions.apple.com/thread.jspa?threadID=1283076
On the Windows machine (that the printer is connected to)
1. hold the start button on the keyboard and hit 'r'.
2. type 'cmd' and hit enter.
3. type 'ipconfig' and hit enter.
4. write down the ip address of the printer's host machine (take note of the subnet while you are there
if you want to tinker with getting the workgroup setup working later)
5. open control panel.
6. open the printers option and write down the name of the shared printer you want to use from the mac. At this point if you see any crazy characters in your printer shared name or you don't want to type in a 255 character printer name, naming the printer something smaller is advisable. For the purpose of this, I renamed my Canon PIXMA iP4000 - Office to "pixmaip4000" and just reinstalled the printers on the windows machines to find the new name.
7. go back to the control panel and open 'programs and features.
8. on the left sidebar click 'turn windows features on or off'.
9. expand the print services folder and enable all 3 options.
10. hit ok and then wait for the dialog to go away (might take a few minutes). This will take quite a while on older machines as it sets up the LPD daemon and you will often think it has frozen as the bar will sit at 0% for 15 minutes or more before suddenly jumping to 98% and then completing another few minutes after that.
Onward to the Mac you want to print from
1. go to system preferences
2. open print and fax
3. click the plus sign to add a new printer.
4. Click on the IP Icon in between Fax and Windows icons on the top icon bar
5. Set Protocol to : Line Printer Daemon - LPD
6. Set Address to the IP of your windows machine that is hosting your printer
7. Queue should be the name of your windows printer. In my example I used "pixmaip4000"
8. Name can be anything descriptive that helps you tell which printer is on what computer (especially if you have multiple printers hanging out on your network.) Location can be any description that helps you remember where the printer is)
9. select the correct driver for your printer under Print Using.
10. click add
I have included a screenie of the mac setup example for visual reference.
(Random note) After I set up the computer to print this way, my macbook miraculously decided that it could see the workgroup printers. Sometimes working around things gets you right back to the start where you wanted it 3 hours earlier!