RewriteCond %{QUERY_STRING} f=([56])$
RewriteRule forumdisplay\\.php http://www.example.com/forums/%1? [R=301,L]
RewriteCond %{QUERY_STRING} f=[^56][0-9]*$
RewriteRule forumdisplay\\.php http://www.example.com/forums? [R=301,L]
The trailing ? is to erase the original query string
Thank-you for that piece of code. I am going to have to study it since I have 0 experience with this sort of thing. 
Sorry to double post…
[SIZE=2]I was just wondering if you can quickly check if my 301 redirect code is correct:
[/SIZE]
RewriteCond %{QUERY_STRING} cheese=cheese
RewriteRule index\\.php http://www.newsite.com/cheese? [R=301,L]
[SIZE=2]
The reasoning is that my dynamic URLs do not properly match my static URLs. For example:
The above code helps me to redirect [/SIZE]
http://www.oldsite.com/index.php?[/SIZE][SIZE=2]cheese[/SIZE][SIZE=2]=[/SIZE][SIZE=2]cheese to [SIZE=2]http://www.newsite.com/[/SIZE][SIZE=2]cheese[/SIZE][SIZE=2]/[/SIZE] [SIZE=2]
Then, I can modify the above code so that I can redirect
[/SIZE] [SIZE=2]http://www.oldsite.com/index.php?[/SIZE][SIZE=2]cheese[/SIZE][SIZE=2]=articles[/SIZE] to [SIZE=2]http://www.newsite.com/category/[/SIZE][SIZE=2]cheese[/SIZE][SIZE=2]/[/SIZE] [SIZE=2]
which has a completely different URL structure and etc.
As well, I have this code:
[/SIZE]
RewriteCond %{QUERY_STRING} f=10
RewriteRule forumdisplay\\.php http://www.newsite.com/forums/forumdisplay.php/10-Cheese? [R=301,L]
RewriteCond %{QUERY_STRING} ^f=(.*)$
RewriteRule ^forumdisplay\\.php$ http://www.newsite.com/forums? [R=301,L]
[SIZE=2]
The first part allows me to redirect [/SIZE]http://www.oldsite.com/forumdisplay.php?f=10 to http://www.newsite.com/forums/forumdisplay.php/10-Cheese
While the 2nd part redirects any f=# that is not 10 to http://www.newsite.com/forums
It seems to be working for me but I am not sure if this is the correct approach.
[SIZE=2]
Thank-you for your time!
[/SIZE]