To simply put any mic in-front of an amp and profile may not give you the results you want.
Here are some tricks:
Mic placement:
http://www.youtube.com/watch?v=i7ArZ5ElkxE
http://www.youtube.com/watch?v=RyDnoHSFsnc
Here is a nice video with two classic guitar mic's
http://www.youtube.com/watch?v=NzApGNWmVTE
Some more stuff:
http://www.youtube.com/watch?v=ZNRp_r1yqFY