Sorry I'm a little late, this is my first time here ( so I signed up for an account so I could answer you.)
If you go to your printer properties on computer B Start>Settings>Printers and faxes> right-click on the printer you want and select properties...
then choose the "sharing" tab you should see "share this printer" select that and give the printer a name.
Now when you look for new printers on computer A should should see that printer with whatever name you gave it.
Oh umm... if you have a Mac I have no clue how to do it.
(don't worry I won't normally revive such old threads, but your question was never answered.
)