From my reading, your points are:
1.  Canadian involvement in Afghanistan will not prevent terrorism from happening;
2.  Terrorism is routed in many areas;
3.  Terrorism is one big jigsaw puzzle;
4.   More immigration conditions at home.
5.  Summary is questioning why Canada is in Afghanistan. 
The current "war on terrorism" conflict is not unlike anything else that has happened in the last 
2.5 million years of human history.  More recently, there are causes, effects, and consequences 
affecting 19th and 20th historyin regards to Europe, the US, Russia, China, central Asia, old 
empires, authoritarians, Afghanistan, warlords, the Taliban, and Al-Qaeda, and Al-Qaeda 
wannabees.  This sets the context, those who ignore geo-history are  doomed to repeat it.
Canadian involvement in Afghanistan is affected by the attacks performed by Al-Qaeda on 
our allies, the cells and documented terrorist activities occurring through and within our borders, 
threats made against our country by terrorist organizations (Al-Qaeda and Hezbollah directly), 
and terrorist intimidation of Canadian interests  overseas.  Can it be argued that Canada is involved 
whether we want to be or not?
Afghanistan was the major physical training region for Al-Qaeda for some time.  Taliban 
support of Al-Qaeda is a fact.  Since the Taliban would not cease their support of Al-Qaeda in
the light of 9/11, the US/NATO had the means to take the fight to the region.
Canadian continuing involvement in Afganistan reduces the ability of old Taliban elements 
returning to power, stops further physical support of Al-Qaeda in the region, and reduces 
one area/support structure in which ourenemies can exploit.
The US and other countries are pressuring African, Middle East, Central Asian, and SE 
Asian governmentsand NGOs/other from supporting AL-Qaeda through diplomacy, the UN, and 
financial/military threats or incentives.
If Canada was to remove itself from Afghanistan, or countries of interest, the warlords and 
Taliban authority figures with weapons would once again take power in the various AFG regions 
and any rule of law or humanitarian undertaking developed would disappear.  Al-Qaeda would
gain further support and that is not in Canadian interests.
In another sense, global conflicts like this cannot be solved simply in one day.  Theres no easy 
solution.  Most conflicts are based on actions, counteractions, strategy, consequences, that play 
out until there is a conclusion.  Continuing involvement by countries in Afghanistan will allow the 
establishment of the rule of law in the long term and eliminate the return of terrorist support.
As far as domestic Canadian policy affecting immigration, the charter of rights, and various 
Acts, ...well...good luck with that.  Old country problems brought into Canada from first generation 
immigrants and idealogical festering in cultural ghettos can be in conflict with Canadian laws and 
main-stream social value.  I know a Chinese restaurant owner who served in the PLA 
(or so he said).  He said if the US and Canada ever went to war against China, he wouldn't be on
 our side.  I have no idea how much fact or bravado was in that statement.  However, it kinda 
bothered me as this is IN Canada.  Despite this, I've seen this guy hand out food to hobos, help 
people off the street, engage anyone in conversation, and seems like a decent enough guy, 
even more than most.  Complicated issues that cannot be addressed in bi-polarized
discussions.  Good luck with that.
** Since typing this up, there were 23 replies to the thread.  Holy Cr*p! I have no idea whether 
anything I've written is relevent anymore (or ever was so) but I've spent enough time that i'm not 
deleting it so I'm clicking post...