NEED HELP! for PS3

The games will depend on the format. For eg, some regions are running video formats in 'PAL' while others are running in 'NTSC'. So you need to check what format is being run in Argentina and Canada. If both are the same, there should be no issue. However, if they are different (for eg, Argentina is 'Pal'P and Canada is 'NTSC'), then you may have a problem.

You should buy the format being run in Canada since that's where the games would be running eventually. From what I've managed to figure out, PAL-N variant is used in Argentina. Source: http://en.wikipedia.org/wiki/PAL

For Canada, it seems to be NTSC-U/C (U/C refers to U.S. + Canada). Source: http://en.wikipedia.org/wiki/NTSC
 
All PS3 games will work on any PS3, regions don't matter at all.
The ONLY thing that you will have problems playing on your PS3 are movies (DVD, Blu-Ray) from different regions. US-NTSC, NTSC-J, PAL.