Mac Pro Problems After Installing Software

I recently upgraded to Snow Leopard. I then installed Nikon Capture NX2, then I tried installing the software for the Canon Pixma 870 printer. I am working on a Mac Pro. I am a recently retired photographer.

When I first installed the Canon software I had to quit as I could not get the computer to recognize the password for the Airport Extreme wireless connection. I could go no further. So I quit the install. The drivers were evidentally installed at that time. After a week I reinstalled the canon disc and did the install over the top of what I had there already. Problems ensued. Now, I have a slow start up and a lot of force quits.

I did fsck -fy several times and got it partially straightened out so that the computer functions, though, not fast as it used to. I know I screwed up but I was not sure how to remove the Canon software properly with the MP. I need an education for this procedure and what to do to fix the HDD which I thought was the problem before I realized that I was the problem.

To this date and several attempts I cannot get the printer to function on the Airpost Wireless and the computer is a mess also though it is working, albeit, slowly.