March 2003 Irvine Underground [irvineunderground.org] the group built cantenas out of numerious cans and wrote about it on their site, each device was tested. This is something I participated in. The graph results were located here [irvineunderground.org].
To connect the antena your WiFi card needs to support external antenna. From the graph above it may be wise to use something other than pringles ;) Pringles was to the far right :) You will need to built the pringles can into an antenna and use a pigtail connector to connect the two together.
If its a on-board WiFi card and doesn't have the external antenna spot search around see if anyone has done it before.
If its a card that goes in the little slot buy a card with external antenna connector to it.